Urgent Please Help!!

I recently had terminated my 5-6week pregnancy on the 26th of February and started birth control pills the following Sunday. After my abortion i experienced bleeding, heavy and light for about 12 days until it completely died off. I just finished the whole first pack of my birth control pills yesterday and i still have not gotten my period. However, i did bleed ONCE during the week i was supposed to get my period (the last row of pills). I bled a tiny amount after feeling crampy and then afterwards i just had brown discharge and that only lasted for 2 days. I'm super worried right now because i am sexually active and my boyfriend and i did not use condoms. Is there anyone who can explain why this is happening? I don't want to jump to the conclusion just yet that i can possibly be pregnant again because i will be torn to pieces.