Wellbutrin and lack of energy

I have been on WB 300mg for about a month now. I have had headaches on and off, lack of energy and an upset stomach to the point of almost vomiting almost every day the past couple weeks. I have not noticed any improvements in my depression. I know it is very common to gain weight on most antidepressants (which would just bring on more depression) but less common with WB which is why Ive decided to try it. Can anyone tell me how long I should stay on WB without improvements before giving up and moving on to something new?

I am on my fourth day weaning off Wellbutrin after two weeks of every other day. (I have been on 150 mg.) I went on it to combat sexual/lack of energy side effects of Paxil. Went off Paxil (which was HELL) in Sept. Liked the energizing effects of Wellbutrin, but in the past few months I have been very, very irritable, argumentative, prone to road-rage, etc. I am getting married in four months and want to make it to my wedding day! I also have been getting heart palpitations, itchiness and insomnia. But the killer for me is the mind racing and irritability. I am incredibly fatigued without my "speed," but I'm looking forward to being a sweet, if a bit sleepy, person again.