Wellbutrin and felt nothing

I have been on Bupropion SR for about a month now. I had severe depression stemming from past incidents that I was unable to get over on my own. I started at 150 mg once a day and the first 2 days I felt nothing. The third day I caught myself grinning and laughing! However, on the 5th day, my doctor upped it to 150 mg twice a day. After the fourth day of that I started feeling irritable and tired. After a week of it I started feeling dizzy, nausea, anxiety, shaky, and just generally weird. I went to a different doctor and told her the symptoms and she reduced me to 100 mg twice a day. The dizziness is gone but the irritability is still present although manageable if I just think before I speak. I also have lost about 5 pounds. I notice that some days I have no appetite and others I am ravenous. The worst side effect so far is the anxiety. I have never had it before and now when the least little event or conflict is present I start getting a churning feeling in my stomach and restlessness. As for insomnia, I do stay up too late but once I force myself into bed I pass right out. I get sleepy around 2:00pm which is when I take the second pill and sometimes can't stop myself from falling asleep at my computer at work. My dreams were more intense and lucid when I was on 300mg a day but they seem to have gone back to normal now.