One of the biggest problems of being an adolescent is that you really have no one to talk to about problems that every adolescent has and that often as not get resolved as you go into early adult hood.
When I was 17 years old, 48 years ago, I could have written a letter identical to yours, as could most my friends who were not part of the social elite in my high school. I found out later that some of those in that special elite group were experiencing everything I was also.
So the question is whether your feelings are part of your age experience or part of your natal chart?
My suspicion is that they are more of the first than the second. I'm sure that someone will comment on your chart. After saying this, you might expect me to do so, but I have an ethical issue of not being able to do chart work for children(I know you don't see yourself as a child, and in a real sense you are not) under the legal age of 18.
My suggestion before you get too deeply into astrology which incidentally is more complex than you can imagine at this time in your life, that you find a friend who is about 22-26 to talk to about these concerns.