Could spotting when due for your period be implantation bleeding?

[ToriMedrano]

Im on birthcontrol, and last weekend I missed two pills and i did have unprotected sex. Ive been on the antibiotic Amoxicilin because I got my wisdom teeth out a week ago. Ive heard antibiotics could lessen the affect of birthcontrol but I didnt know it was an antibiotic when I started taking it because I was in too much pain from the surgery I just took my percriptions and slept. Ive had normal periods on this birthcontol for over a year always painful and heavy. I always get my period on the third day. Last thurs I stopped taking my pill and i expected my period on saterday but it never came. I lightly cramped and spotted red blood but there was barely anything it was litterally spots. The cramps lasted a few hours then everything completely stopped. Could i be pregnant? When should I test?