Plan b

Just curious if anyone has been in a similar situation. I had sex on September 12th and it was unprotected & while we were doing it he told me he had came in me and we just kept having sex after that. The next day maybe 17 hours later I took a plan b but I just found out if you weigh more than 175 pounds it doesn’t work. I’ve been having the side effects of plan b and my period is late from the plan b. But that weight limit still has me scared? Has anyone been in the same situation?