To be honest, I am more concerned about your bulimia. You aren't getting nutrients when you purge, so this will definitely have an affect on your baby's development. Of course, smoking cigs/pot is not good either, but I don't think past use would necessarily cause a future miscarriage. It might if you continued. When you go to the doctor, explain to him honestly what's going on and ask for help. You'll be given prenatal vitamins, but also the doctor may suggest certain nutrient-packed foods that aren't great sources of fat if that's a concern to you. Make sure you get folic acid and protein through foods and supplements. He may also give you some help tips on staying away from the cigarettes and pot, too. Good luck and if you need to talk about the bulimia (or anything), feel free to email me. My aunt went through her last pregnancy fighting anorexia/bulimia and I've had two kids myself (smoking [cigs] with one pregnancy).