Is it possible for implantation bleeding to occur 3-4 days after conception?
It is possible but not very likely. It’s probably more likely that you had an ovulation bleed, which is caused when the egg breaks out of the follicle holding it into the fallopian tube if it happened about 2 weeks after your last period. But even if that is the case, it’s still possible the egg could get fertilised so you should probably take a test about a week after your next period’s due. Being on birth conrol can cause you to have a bleed when you expect your period even if you’re pregnant so don’t rely on missing it to tell you. Try not to worry too much though, it’s still quite unlikely.