I’ve been committed to mechanics and physics since I was in high school.

or "I've committed myself to".

I’m currently studying master'sfor my Master's degree at university.

I started primary school when I was 7 years old.

Later at 12, I went to elementary school at 12.

Just a little more natural to read.

In my country high school lasteds 4 years, t. Then I went on to higher education at my hometown university, from where I graduated one years ago.

Actually, I was quite good at math and physics back then.

"Actually" is moreso used when the target believes otherwise, we have no reason to believe that you weren't good at maths and physics from what you've told us.

Besides I was interested in English & Literature.

Although alll of my math & physics teachers were awesome and dedicated, so I tryied my best to get high scores and impress them.

"Although" would imply there's a contradiction somewhere, even though your sentence is consistent. The second change is a correction of the tense.

As I have always been fascinated by how mechanisms works, I felt that mechanics was the ideal field of study for me.

Additionally, I’ve already explained my long-term interest in mechanics.

I don't really understand what this sentence refers to.

To tell you the truth, it was quite challenging for me at first because the university’s requirements are high, besideas science itself highly demands skillful hands, a curious mind, and problem-solving skills as well.

However, as time goes by I’m getting used to anthe previously insurmountable amount of pressure and am actually enjoying my study.

It’s great to join the workforce, especially when I can do the job I love.

The workforce is a concept of sorts, so we use the definitive article.

Not only will it pay the bills, but it will also give me the joy of making a new mechanisms to give handassist to people.

Study

An incomplete title. Consider "My studies" or "Studying".

I’ve been committed to mechanics and physics since I was in high school.

or "I've committed myself to"

I’m currently studying for my master's at university.

I started primary school when I was 7 years old.

Later, I went to elementary school at 12.

Grammatically sound. "Later at 12, I went to elementary school." is more natural.

In my country, high school lasted 4 years, t. Then I went on to higher education at my hometown university where I graduated one years ago.

Actually, I was quite good at math and physics back then.

"Actually" implies that the reader initially believed you were bad at math and physics.

Besides I was also interested in English & Literature.

Although all my math & physics teachers were awesome and dedicated, and I tryied my best to get high scores and impress them.

I'm not sure what you were trying to say here. "Although" implies that normally you would only want to impress teachers who weren't awesome/dedicated.

As I have always been fascinated by how mechanisms works, I felt that mechanics was the ideal field of study for me.

Additionally, I’ve already explained my long-term interest in mechanics.

Not sure here what the "already" refers too, but this is grammatically sound.

To tell you the truth, it was quite challenging for me at first because the university’s requirements are high, besides. In addition, science itself highly demands skillful hands, a curious mind, and problem-solving skills as well.

However, as time goes by I’m getting used to anthe (seemingly) insurmountable amount of pressure and actuallyt university and enjoying my studyies more and more.

Getting used to insurmountable pressure is a paradox :)

It’s will be great to join workforce, especially whenif I can do the job I love.

Not only will it pay the bills, but it will also give me the joy of making a new mechanisms to give hand tohat help people.