lol of course you can go without a teacher... I've always hated when people criticized my work... Yeah, I really did.. That's not good is it? lol
Anyways, I'm not saying my drawings are all perfect, but I think I'm doing ok, and I reached here all by myself.
People say that if you practice you'll get better, but that's never enough. I think that you got to love drawing to get better at it. You only need motivation and a good pair of eyes to observe. And hey, you have skills and worrying to the point of going to a class to get better shows you reallylike drawing, so yeah! Keep it up!