I'm doing many things on a day.

My to-do list is so large that a day never seems to be overenough to cover it, and honestly that feels right.

Two hours for each children.

Before, II used to sometimes felt like thatel that, this kind of life wasn't for me.

I'm have been doing many things on aevery day.

"Last couple of days" puts the tense to include the past and the present, so adjust accordingly. I only understand from inference what you mean by "on a day"; I think you mean something like "every day".

Before, my morning felt like two hours now Iit lasted two hours. Now, it really feels like the middle of the day.

I added clarity and continuity with "it lasted" and "Now".

I think that's because I go to the gym very early, literally right after going tofor a 10 minutes walk with my dog and eating the middlehalf of my breakfast.

"right" adds clarity. Otherwise I just corrected grammar.

After doing exercisesing, I have to work.

Unless you are referring to specific exercise routines, I would use the verb.

My work ijob involves giving tutorials to a children and some teenagers.

When presenting your work in this manner, it sounds better to refer to it as a job. You can redact the pronouns here.

TI spend two hours with each children.

Your original sentence isn't complete, so I completely revised it with something that could work.

So I think that's why my mornings feel more longer than ever.

In the afternoon I have my pre-professional practices, l. Luckily, the schedule and the rules there are very flexible.

For general audiences, it might be worthwhile to describe what a pre-professional practice is. This segment is best separated into two sentences.

In little words, I have to doTo sum it up, I make digital content for a clinic's social media and n. Now, we're domaking a short film.

"In little words" isn't natural sounding. With your repeated use of "have to do", it begins to come off that you don't really enjoy your work; Doing this also lengthens your sentences. In this case, you can cut down by just saying you make digital content instead of emphasizing that you have to make it. This segment flows better when separated into two sentences.

Besides, Bbecause of how flexible the schedule is I can have a class in the afternoon with other kids.

The continuity between this sentence and the ones coming before feels broken.

Later, I havtake some free classes that I found online, sonline classes. Sometimes, they start at 7PM or 8PM.

Ditto for sentence separation. Otherwise I shortened, improved grammar, and naturalized this segment.

When I'm not doing that, I'm just watching videos of other classes I have,: classes that I cannot attend forbecause I am too busy doing other things.

A comma after the preposition and colon instead of the original comma improves this sentence's grammatical flow. Clarifying that doing other things makes you busy makes the causation a lot clearer.

Those are kinda my days now and I really enjoy each one.

Something a bit more natural sounding would be something like: "Nowadays, this is how I spend my days"

I'mve been doing many things on a given day.

Before, my morning felt like two hours now It really feels like the middle of the day.

I didn't understand what you are trying to say here.

I think that's because I go to the gym very early, literally after going to a 10 minutes walk with my dogwalking my dog for 10 minutes and eating the middle of my breakfast.

I'm not sure what "the middle of my breakfast" means. :-)

After doing exercisesworking out, I have to work.

My work is giving tutorials to a children and some teenagers.

I'm not sure whether you meant "to children" or "to a child"

So I think that's why my mornings feel more longer than ever.

In little wordsbrief, I have to do digital content for a clinic's social media and now we're doing a short film.

Besides, Bbecause of how flexible the schedule is I can have a class in the afternoon with another kid.

Later I have some free classes that I found online, sometimes they start at 7PM or 8PM.

Those are kinda my days now and I really enjoy each one.

Alternative:
That's an overview of my days now, and I really enjoy each one.

But now, I realize that I'm capable of doing this and (many) other things as well.