My unforgettable birthday

This is fine.

Last year, it was my birthday number twelveI turned twelve last year.

It’s more natural to say ‘my twelfth birthday’ or ‘I turned twelve last year.’

I woke up at 6:30 AM because I had to go to school.

You can add AM but it’s fine to say it like that.

When i arrived at school, my best friend oli gave me a ring and a letter, i love the rings i have a lot.

This is to split the sentence and allow for pauses to be made.

Then we studied Maths and French.

This is good.

After that with, all the girls ofin my class went to my house for a piajama party.

The corrections were made because “in my class” is the correct preposition for belonging to a group, and “pajama” is the standard English spelling. Also, add a comma.

We ate hamburgers and snacks.

This is fine.

Then we saw Inside out 2, it was very interesting and funny.

This is good.

Finally we went to bed.

This is fine.

Last year, it was my twelvth birthday number twelve.

When i arrived at school, my best friend oOli gave me a ring and a letter, i. I really love the rings i have a lotI already have.

There's nothing actually incorrect about "a lot", but it sounds clumsy when you put it at the end of a sentence like this. I added "already" to make it clear that you're not talking about the ring Oli gave you.

Then we studiehad Maths and French.

Studying is not used when you go to a lesson. You can say "I studied Maths at university" or "I studied Maths in the library after school", when when you attend a lesson "I went to Maths" or "I had Maths"

After that with all the girls ofin my class went to my house for a piajama party.

Then we sawwatched Inside out 2, itwhich was very interesting and funny.

Last year, it was my birthday number twelve.twelfth birthday.

When iUpon arriveding at school my best friend oOli gave me a ring and a letter, i. I love the rings iand I have a lot. of them.

After that with, all of the girls ofin my class went to my house for a piyjamas party.

Then we saw Inside oOut 2, i. It was very interesting and funny.