Jenny it might be sometning as simple as a dose increase. Being that you feel bad when you stop, I am sure you need the medication. I would let the dr. know that after a while they don't seem to be working and the dr. should adjust your dosage. I guess we have to realize that not every day is going to be good, but we should have more good days than bad.
Try to keep a positive additude. You sound like the type of person that can do that. I think if you talk to the doc that you will end up doing well. In the meantime keep posting, we are here for you. Do you have any special interests or hobbies, that helps a lot. Though I know when you are working that it is hard to find the time.
Good luck, and keep us posted.