theres a possibilty usually after getting off birth control most couples take a while to conceive and start ovulating so its a very very very slim chance your even pregnant at all.
whyd you stop the birth control? id suggest getting back on some sort to prevent pregnancy scares in the future.
im not familiar with wellbutrin because i am not allowed to take it. but alot of them cause nausa and drowsiness and stuff like that. if it continues and is bothersome go back to your dr and try and get a new med. are you in therapy or anything? i hope your doing ok and that the meds help you out , there is a depression forum on here too and they are all really nice.
if you ever need to talk i am here as well, been through it all