First, I agree with Karen, you should really consider discussing your feelings with a counselor, and school is a good place to start.
I can relate to you in several ways: I too am new to this site and this is my first posting. I was recently diagnosed with depression and am doing all I can to educate myself on effective ways of dealing with my emotions. Because of this, I have been examining my past, and in doing so I realize that several times in my life I've dealt with being down, and wanting to escape. One of those instances was late in high school when I really wanted to escape from my hometown and my family. I went to college as far away as my parents permitted, which was 4 hours away. When I got there, things were much worse. My feelings of isolation were only magnified, and I actually felt much more alone than ever. I was so devastated to realize that after years of longing to be independent, I felt a loss of identity being completely detached from the former life I'd led. College life is very different from high school, and being at a school a little closer to home may have eased some of the challenges I faced, while still allowing me to explore my new independence. Instead of enjoying new friends and experiences, I found myself longing for the comfort and stability that home had always provided. In high school I was very involved in many extracurricular activities, and my job, and found myself at home mainly to sleep. So I thought it would be no big deal to be farther away, as I'd spent little time with my parents anyway. But looking back, I think that if I had been closer to home, like close enough to travel home even for dinner (maybe an hour or two away), that my college experience may have been much more fulfilling. And maybe I wouldn't have found myself in the position I am today. I digress...
Anyway, I too had a very strained relationship with my father. My homesickness at being so far away did bring out a side of him I hadn't known before, and he opened up to me a few times with handwritten letters, and some emails; things he'd never shared with any of my older siblings who'd never strayed as far as I did. We never really came to truly understand each other, but we did come to respect each other's decisions, and positions in life. I think that for parents, one of the hardest times in dealing with their children is when they are on the brink of adulthood, where you are now. Your father sees you as the kid you were only a few short years ago, and since you are mature for your age, he may not be ready to face the fact that you are ready to make your own decisions, whether they are in agreement with what he might choose for you or not. That also is probably a difficult place for him. He has been making decisions in your best interest your whole life, and letting go of that control and allowing you to find your own way might be taxing his emotions right now.
I don't know. I don't know him, and I can't speak for anyone but myself, but I do know that it is a very helpful thing to get your feelings and thoughts out of your own head, so kudos to you for taking that step and posting here.
Best of luck and best wishes to you.