I need help!!

Ok so, I'm on the pill!! This is my 2nd cycle with it, last month was normal, I had my period and everything on the 4th day of sugar pills.

However, This month, today was the day I should be getting my period, but instead I just had a very light brownish spotting which I thought it was my period, I have never ever experience that before, it has been 2 little drops the whole day.

I have unprotected sex everytime since I'm with my husband and of course on the pill, I have never missed one and took them exactly at the same time every day. It's even possible I could be pregnant?