Have you tried checking for food allergies? I know it sounds kind of hokey, but a mild food allergy can trigger a hypomanic episode... Do you eat the same types of foods often? Is there something that you have daily?
I'd start keeping a food journal and a mood journal and check them against each other... There may be some corrolation there.
Another thing that may have some bearing is when you take your meds.We've found that if my daughter takes her anti-depressant 1/2 in the morning (with breakfast) and the other 1/2 when she gets home from school, she's less likely to go hypomanic (she takes Zoloft), but check with your psychiatrist first... Also if she takes her stabilizer (Depakote) in the morning, she's tired all day and that can lead to hypomanic episodes also. If you're not doing this, run it by your psychiatrist...
Good health and stability to you.
PS. I know that it's hard and that it goes against the effects of the disease, but try to be honest with your family and friends... if you're feeling depressed, let them know. My daughter has a hard time doing this and it makes what could be a small discussion into a major ordeal, for all of us.