I am currently convicted of possession of a forged instrument... a class d felony in nys. I am 6 months into a five year felony probation sentence and am hoping to start college to become a doctor. I am prepared to take all of the pre-req classes at an accredited school, but should I expect any big hurdles?

You should always expect hurdles with a felony conviction. Although it doesn't necessarily mean you don't have a shot. A felony won't bar you from obtaining a license but it will be taken into account. What they will definitely want to see is that you have learned from it and that you have great moral character. You won't have a shot if you don't start doing volunteer work, charity, etc. You'll need references to your character from credible sources as well.

You would have to get a exception, I doubt it will happen.