Missed 4 bc pills & when my period arrived i bled a little then stopped then spotted for the 2 next days, what could it be? unprotected sex many times

Need pregnancy test: Ask your Gyn for a blood betaHCG pregnancy test to confirm that you are not pregnant and if it is indeed negative, consider switching to an intrauterine device (IUD) or a subdermal implant. These long-acting-reversible-contraceptives are the most effective methods and they are "forgettable". Be safer; protect yourself; use condoms too.