Doubts and Acting

I'm having such crazy doubts lately. They aren't new doubts or anything; they are just flooding in recently. I'm just so afraid that I won't be good enough; I won't be talented enough. Its a tough, dog eat dog world over there in New York and I guess I'm just worried. I really want to do this Broadway thing and the idea of my whole dream failing just causes so much sadness in my heart. I want this so bad.
I'm waiting so impatiently for my theatre class next semester because I seriously want to know if I can act. I've never really had a big enough part in anything to have someone ever tell me if I can truly act. There was so much favoritism/biased opinions in high school that I never knew if I got small parts based on my talents or because of my low status in the school society. I'm hoping that my theatre professor will be open with me and just give me the honest truth about whether I can act or not. That way I can prepare for the future and either work my tail off trying to be better or continue being the actor I might be deep down.