Yesterday was my graduation, and I was so excited about it the previous daysin the days leading up to it.

It took really long for ita long time to start, and there were so many speeches and such that it got boring.

However, it still felt special afterwards.

The same day, buta few hours before the graduation, I sent a teacher a message to thank him for everything he did this year.

I think he i's the only teacher at school who really cares about us at school.

I mean, the others care, but not aso much as him.

He doesn't care about grades andor what the headmaster tells him to do, he just wants us to learn.

When the graduation finished, I was in a kind of in a rush because my grandparents were outside and wanted me to give me a present.

I didn't think so, I thought it could've been better.

It was part happiness because of that, and part sadness because of what happened when I haunged out with my classmates (I felt so excluded).

Yesterday was my graduation, and I was so excited about it the previous daysduring the days leading up to it.

You can just say that you were excited here because you already introduced what you were excited about in the previous section.

It took a really long time for it to start and there were so many speeches and such that it got boring.

Theat same day, but hours before the graduation, I sent a teacher a message to thank him for everything he did this year.

I think he is the only teacher who really cares about us at school.

You can say "he's" instead of "he is".

I mean, the others care, but not aso much as him.

He doesn't care about grades andor what the headmaster tells him to do, he just wants us to learn.

I told him that if it had been possible, I would have asked him to give me my diploma.

"Would have" is more commonly written as "would've" thought in this situation you could say (at least in everyday-speech, probably not in writing) "Id've" (I'm not sure how to spell it).

However, as I knew that it wasn't allowed, I still let him know that he was a teacher I'll never forget.

The "that" isn't wrong just unnecessary.

Every student was to take a photo with three teachers showing the diploma.

The phrasing "was to" sounds a bit formal/stiff, it's more common to say "had to" or "was supposed to".

When the graduation was finished, I was in a kind of rush because my grandparents were outside and wanted me to give a present.

"Wanted me to give a present" isn't wrong but implies that you are the one giving the present. If you wanted to say that they were giving a present to you, then it would be phrased like, "wanted to give me a present".

I don't think that it's technically wrong to say, "finished" instead of "was finished", it just sounds kind of off.

I was with a friend who told me she'd talked withto this teacher, and I was really upset because I hadn't.

Fortunately, we went back in, and my best friend "delivered me" (that's the expression they used) to that teacher, as he had been desperately looking for me.

You can use "he'd" instead of "he had".

We hugged and got to talk alone and he told me that what I had written to him was very beautiful.

You can use "I'd" here instead of "I had".

I didn't think so, I thought it could b've better.

It's "could've" instead of "could be" because it happened in the past.

I'm afraid I only heard half of what he told me because I still couldn't believe I had hugged and was talking withto a real human being (we had online classes all year).

It was a moment that was very special to me and that I'll always cherish.

You could also rephrase the beginning of the sentence as, "The moment was very special to me", but you don't have to.

I regret not having taken a photo with him and not having told him that I would have been awfully sad if I hadn't talked to him.

Here you can either say "I'd have" or "I would've", though both are interchangeable. "I'dve" would maybe be used here in everyday speech but I don't believe it's correct grammatically.

When I got home and went to my bedroom, I started crying, which I honestly hadn't thought I would do.

Here you can say "I'd" instead of "I would".

It was part happiness because of that, and part sadness because of what happened when I had hunged out with my classmates (I felt so excluded).

But I won't write about ithat because I wrote very mucha lot already.

Yesterday was my graduation day and I was so excited about it the previous daysly.

Your sentence was correct, I just think it flows nicer this way.

The same day, but hours before the graduation, I sent aone of my teachers a message to thank him for everything he didhad done this year.

You should use the past perfect tense here, because the actions of your teacher were done before a certain point in the past (in this case that point in the past was you sending him a message).

I mean, the others care, but not aso much as hime does.

However, as I knew that ithis wasn't allowed, I still let him know that he was a teacher I'll would never forget.

"This" instead of "it" sounds a bit more natural in this particular scenario.

Every student was to take a photo with three teachers show, holding the diploma.

So I knew that he'd read my message when he tookafter taking the photo with me (he hadn't responded).

I am not sure if I understood correctly! If you meant that he hadn't seen the message yet and you figured he would see it after taking the photo, this would be the way to say it.
But if you meant to say that he'd seen the message before taking the photo but hadn't responded yet, you would say "so I knew that he had read my message before taking the photo with me."

When the graduation ceremony finished, I was in a kind of a rush because my grandparents were outside and wanted me to give me a present.

I had never felt that important or special before, it felt so nice.

When I got home and went to my bedroom, I started crying, which I honestly hadidn't thoughtink I would do.

It was part happiness because of that, and part sadness because of what happened when I was hangeding out with my classmates (I felt so excluded).

But I won't write about ithat because I wrote very much've written a lot already.

Yesterday was my graduation and I was so excited about it in the previous daysdays leading up to it.

Just sounds less awkward

It ended up being pretty boring, if I'm being honest.

To be honest you don't really need the comma since this is pretty casual writing, but if you want it perfectly grammatically correct then I think you should add the comma.

I mean, the others care, but not so much as hime does.

Again, you'll find loads of people who write it the first way, so I guess you're not "wrong" if you write "him," but if you want it perfectly grammatically correct then you need to say "he does." the reason is because you need to keep the two different nouns "parallel" — you see "others care" is a noun + verb, so you need to make "him" into a noun + verb, which is "he does."
Another example would be like "playing video games is more fun than books." You would have to say ""playing video games is more fun than reading books."

Fortunately, we went back in, and my best friend "delivered me" (that's the expression they used) to that teacher, as he had been desperately looking for me.

Could you say "brought me" instead of "delivered me"?

I regret not having taken a photo with him and not having toldtelling him that I would have been awfully sad if I hadn't talked to him.

When I got home and went to my bedroom I started crying, which I honestly hadidn't thoughtink I would do.

to be honest I think both ways of writing this sentence would work, but I personally feel like the corrected way sounds less awkward

It was part happiness because of that, and part sadness because of what happened when I haunged out with my classmates (I felt so excluded).