I just found out I am 11 weeks pregnant.

I have been doing drugs, and drinking lots up until about three weeks ago.

How do I know that it will be okay, or is there anything that I can do from now on, other than the obvious of stopping? Like, what are the odds that it will be affecting? Help.

In all honesty, the odds are different for every woman. You do not mention what drugs you have been using and that is very important.

The first trimester (first 12 weeks) is the most important in fetal development. It is very important that you discuss your drinking and usage with your doctor so that he/she is aware of this and orders the appropriate tests and ultrasounds.