Is it just shyness
The thing that helps me, when I have to talk in front of a bunch of people is I know my material inside and out, I take a deep breath, I make eye contact with everyone before i begin to speak, this makes me know they are paying attention and then it is my job to keep their attention.
Besides, in college and later on in your career whatever it may be, you will probably never see these people again the next term, so it really doesn't matter, and everyone botches. Turns red, gets impatient, especially freshman year.
What I do, is find someone I know who will be worse than me, they are really finnicky, and then I just say, it don't matter how bad or good I do, just as long as I am better than that.
It helps
Don't let something like this prevent you from going to college.
I would say go for small group settings, its awkward at first, even announcing your name and how old you are in some classes when you first start, but I would say being comfortable is key to speaking......
It's a tough situation, but it's good you're finally motivated to make a change. I would recommend you read the Dale Caregie's series, I haven't read them yet but a good teacher of mine recommended me to read it, and he's the kind of guy who only suggests reading the best.
Understand that this isn't a thing that anyone except yourself can really answer and address. You have the confidence -- everyone does. It's whether you decide to use it or not that makes the difference between shy people and outgoing people. You can make the excuse that you get sick/nervious/anxious before/after speaking in front of others, and say that it's too hard to overcome, but that won't hurt anyone except yourself. I'm not saying that to sound mean, but to help you realize and understand and acknowledge that you can do it. Practice small situations where you can use confidence and methodically move onto situations that require more. And keep using it, otherwise it'll slowly go away or others will take advantage of you because you don't use your confidence to give a strong, positive appearance to others.