It sounds like you are a great kid who is really making something of your life!
I recommend some research. Make an appointment with the guidance counselor. Bring all your records and find out exactly where you would stand for graduation.
Then, contact some admissions offices at colleges you are interested in. Find out what their homeschool admission policy is. Ask them if any homeschoolers have won their top scholarships (almost certainly they have). Ask them how their admissions committee views homeschooling.
Then bring the information to your parents. I think you and they will find that you are much better off staying at home for your senior year. I know a homeschooler just won one of ten full-ride plus scholarships at my husband's alma mater. My own son has been highly recruited and offered several scholarships already -- and he's been homeschooled from the beginning.
I think if you come to your parents with hard facts, you'll be in the best position.
I also recommend that you think about someone in the community who could right the guidance counselor's letter for you, since your parents don't seem too engaged. Is there a librarian or homeschool support group leader who knows you well?
I hope this all works out great for you!