What Causes Delayed Period While Having PTSD And Bipolar Disorder?

I am 21 years old, 5'5", 300 pounds, and I have been diagnosed with PTSD and Bi-Polar disorder but I'm not on medicine for either at the time. I haven't had a period since Feb. 28th 2011. I have unprotected sex with my husband all the time, I have taken HPTs all come back negative the last one I took was Saturday morning. Now I am spotting after orgasm. Any thoughts on what's happening?