The transition you're about to go through is tough but I think you will probably benefit from the new environment and resources available to you.
First of all, welcome to the boards. I can't remember the last time I've seen someone say openly "I'm a girl and new to forums" so I feel compelled to offer some advice you didn't request. I'm coming from a similar place. I'm around the same age as you and I'm in college. Have been on the internet way, way too long and got into online communities way before I should have. Typical stuff. There are a few girl-centered IBs out there that you will inevitably stumble into if you actively look into what IBs are, but I strongly strongly recommend against them. There are a lot of people that promote pro-anorexia through various means (even if it's against the rules) and the politics that have sprung up over the years have bred some of the least productive, most toxic communities I've ever seen. As they changed, I started to notice the way I thought about/processed the world change as well in a really negative way, and I stopped using them. Just my sincere words of advice from one stranger to another, don't let your mindset become toxically affected by any community online.
Eating disorders are so difficult and misunderstood. I'm really sorry you're going through this.
First thing is, when you get to college, you're probably going to have *free* access to mental health services. Please use them. Usually counseling in college is specially prepared for helping students with eating disorders. Yes sometimes it's hit or miss at some places but a professional environment *will* help you. A lot of times people get cold feet or feel like it won't help them after a couple of sessions. Keep pushing and attending. It sounds like you really want to make positive changes in your life and already kind of understand some of the underlying issues so it will probably be effective for you or at least start you in the right direction.
Secondly, I just wanted to say that, whatever condition your body is in or however you look, whatever weight you are, you are still of value. I know the self-hatred stuff over physical appearance is deep-rooted but sincerely, you have a disorder, and it is okay to struggle. It's okay to not be doing well. We take things one day at a time, look for the next step, and forgive ourselves for yesterday. It took me so long to learn that.
Last thing I picked up from your Post too long. Click here to view the full text.