hello, after having nursed for a total of 8 years I guess I can offer you a guess. I don't know poo about wellbutrin and appetite though as you mention it I lost a bit of weight over a several month period since starting the med in June I believe. However, more important then calories is fluid for your milk. I drink hot water in the winter, seltzer in the warm. I drink like a camel and I know that is the main issue with quantity of milk. As for quality, your body robs mom to feed baby so take a multi vit with food in the a.m.? Your baby will be okay with milk, supply and demand as long as you drink a lot of fluids but do take a vit or two until this settles out okay? Good luck. By the way, I NEVER lost weight nursing.