Hi Martha If I may, I have a few of suggestions
Firts I would suggest you changing that word "OBSESSION" makes it sound like something wrong or sick, since you are talking about the emotion or the feeling that inspired you, you might as well try to find a more suitable word for example enthusiasm.
In the sentence "It was this overboard obsession I had with the idea of the medical field." I found it somehow vague because it looks like you are going to imply into something but then you just stoped, so you cant try to rephrase it.
I have one last suggestion, of course, with all due respect.
take a look into this.
"I pursued my goal by applying to a technical high school that offered courses in the Health Academy. And so I chose to be part of the Pharmacy Program. I knew that enrolling into this program would mean that I would have to sacrifice my time in order to persevere and achieve my goal".
"In order to persue that goal, I applied to a technical high school which offered courses in the health academy, and as an example of my dedication and perseverance I decided to enroll into the pharmacy program, which meant sacrifice but also an important step towards my goal".
The first lines of your essay are ok as an introduction but then try to give it a more formal touch. They are asking you for the qualities or unique characteristics you possess, so first find some "keywords" such as perseverance, dedication, or the ones that you think you possess, and from there start composing your essay.