When Seroquel first came out -- which was pretty recently -- Psychiatrists loved to prescribe it because it was supposed to be completely non-addictive & totally safe, which was complete & utter bullshit. I've been on & off [mostly on] Seroquel for years & years, & I'm just as addicted to that shit as I am to the Benzos I've been taking for years [okay, not AS addicted, but close]. Not only is Seroquel very quickly developing a reputation for being more & more unsafe with common side effects that just aren't worth it, but, Seroquel works by lowering your Dopamine levels. Considering Wellbutrin works by increasing your Dopamine levels, it definitely doesn't seem like a very sensible medication regime for you to be on.
I'd HIGHLY HIGHLY suggest just getting off Wellbutrin, since it seems to be having a very negative impact on you. You should NOT have to take a medication to deal with the side effects of another medication you're taking... That's just generally a bad path to go down. Plus, it seems to be hurting your mood more than helping it.
Have you ever tried any other Anti-Depressants, particularly SSRIs [Zoloft, Prozac, Lexapro, etc. ?] If not, I'd DEFINITELY suggest getting off Wellbutrin & switching to one of those.