Hi.
Your feelings are not an overreaction--they are normal under the circumstances. You've gone through a very traumatic experience and it's affected you deeply. I'm sure your trust in people has been damaged, especially since the guys who did this were people you considered friends. I'm not surprised that you are now suspicious of even friendly touch.
Some people aren't able to cope with the feelings and physical reactions brought about by an extremely stressful event. They might experience such things as re-living the event in one's mind, being unable to sleep or having nightmares--and it is not unusual to find serious problems continuing for months afterward. Since this has been going on for more than eight months now, you may be suffering from more than an "acute" or short-lived stress reaction.
Your thoughts about others having had it "worse" than you may be keeping you from seeking the help you need. You have a better chance of getting better if you resist the urge to downplay what happened to you and acknowledge to yourself (and others) the impact this is having on your life.
Talk to someone you trust. This can be a close friend or relative who cares about you. It may be best to also seek short-term therapy to help you sort through your feelings about the situation. A school psychologist may be able to refer you to a mental health practitioner in your area.
Take care.