Well, I'm seventeen and this year was the last year of my school life, so I had to choose my future profession. I was (and am) interested in physics, medicine and I wanted to be a designer too... All this of these at the same time. I'm a creative person (I'm not a braggart) and the last one could be perfect for me. 

It was hard for me to make a choice, but finally I decided to become a surgical oncologist, because it is a more serious profession and now very usefull for me and my present and future family. (Who knows? Maybe I will be given the Nobel Prize in that sphere field. I hope so.)
What do you think about all of this?

Use ellipses ("...") sparingly because it makes you seem unsure about what you've said. It also interrupts the flow. When you do use ellipses, though, always use three and put a space after. 

Always capitalize the personal pronounce "I."

No period ever precedes "because."

When using parentheses, only use one on either side, and do not add spaces after or before them:

Incorrect:  (( Lorem ipsum dolor sit amet. ))

Correct:  (Lorem ipsum dolor sit amet.)

And be careful not to overuse parentheses, too!

Good work! Hope this helped :)