What Causes Bleeding And Cramps After Taking Plan B?

I ended a pack of birth control pills, and started a new one but took the first week then kept forgetting and just stopped. Two weeks later after a period from my old pack, I got another period for about 4-5 days (normally should be 5-7). I had unprotected sex during that, and my period ended, then had sex again. About 3 days later i took plan b, the first pill and it was probably 4 days from the last time i had sex that i took the second pill (12 hours after the first). A week later I bled lightly I think, for one day. After that I started having cramping, and a weird feeling in my lower abdomen. I started my birth control back up about a week ago exactly. But since i last bled ive had cramping, nausea, been really gassy, i'm sensitive to foods and smells, exhausted. pretty much everything but sore breasts. Its been 2 1/2 weeks since i've taken plan b, and i'm not sure when my period is supposed to come since my period has been screwed up. I do remember one day...probably 3 days after I bled for a day, I had period like cramps. But only for a day, and nothing came. I've taken 3 pregnancy tests and all are negative. I've had unprotected sex a few times since then, and havent taken anything. Just the birth control. My dr. has be on prenatal vitamins just for the vitamins, and folbee tablets, and primrose oil....along with my birth control. I just started the birth control so im pretty sure its not protecting me yet fully. What are the chances I could be pregnant, and when should I take a test? Or expect my period?