withdrawal bleeding is good enough to discard pregnancy if I’m on the pill?

[Dali3425]

So, I had unprotected sex with my boyfriend at the end of October, two weeks later I got my withdrawal bleeding during the week that I took my placebo pills. The bleeding was normal and with clots. Then I started a new box of pills and took them as normal. I have a long distance relationship with my bf so I haven’t seen him since October. During the week that I took my placebo pills, this last time (first week of December) , I didn’t get my withdrawal bleeding or got any symptoms of PMS. Now I started my new box of pills as normal but I didn’t get the withdrawal bleeding. I just wanted to know if there’s any chance that it could means pregnancy, since I didn’t had sex at all after I got period last month. I’m just really nervous, everyone keeps telling me it’s impossible tho.