Confused

I have been on cerazette since summer 2016 and I wasn’t having a period at all but in the last few months I have been bleeding (3-4 days and it’s not spotting blood)... I have always taken my pill at virtually the same time everyday hence why I’m confused about the bleeding etc. On top of this I’m worried that I’m pregnant I had unprotected sex on the 10th of October and since been very paranoid I haven’t had any symptoms other than when I get my short period my boobs get heavy and I feel tired. Is it possible for me to be pregnant and if I was to be would I know ?? I know this sounds extremely silly but any help would be greatly appreciated x