I Am On The Pill, Trinessa, Last Had Sex On

I am on the pill, Trinessa, last had sex on 11/3. The last "normal" period I had was 10/20 and lasted three days. Had terrible PMS (tender breasts, bloating, sore back, cramps, headaches) light spotting and bleeding on 11/17-19. This month I began bleeding on 12/15, began with spotting and now heavier than last month but still not like my normal periods. Prior to this period I had severe bloating and constipation. Now, still bloating and getting headaches but no other symptoms. I know that you can still get bleeding during placebo pills while pregnant if still taking birth control. I have had many negative home pregnancy tests, and two negative urine tests at my Drs office but I still feel anxious about this. Could I still be pregnant or can I trust that these are true negative and true periods? Thanks!!!