As long as you quit those things NOW, your baby would probably be okay. Since you are five weeks pregnant, that means you only conceived about three weeks ago. Doing those things during your pregnancy is a horrible thing to do, but many many women out there have done the same because they did not know they were pregnant yet and their kids turned out okay. As long as you quite RIGHT NOW, your kid would be fine.
However, could you stop all of these things for life? Children with drunken parents are unstable (a few drinks sometimes is okay, but not all the time, and especially not when you are breastfeeding. it could be passed onto the baby that way). Children suffer from second hand smoke and get terrible lungs from it. It's essentially handing your child a cigarette whenever you smoke. I'm sure you'd also know why coke is horrible , so I won't even go into that.
Would you be able to raise this child if you wanted to? Do you have the money? Education? Who is the father?
If not, I believe you are right in wanting an abortion. If you don't think you are ready to handle the responsibilities yet at this age then there is nothing wrong with it. You are still really early in your pregnancy and have time to think things over.
There is also always adoption.
Good luck with your decision.