Could this be implantation?

Victoria
So my boyfriend and I (both of us are 18) had sex for the first time 3 weeks ago. It was protected sex, no holes or leaks in the condom and he didn't finish in me 100% (I finished him afterwards with head so I know this.) we also only had sex twice (both times completely protected.)
I've been panicking all month about pregnancy.
Anyway, this morning I have some blood and I'm not sure if it's my period which is pretty irregular (today is day 31, I'm usually between 30-40 days) or if it's implantation. But I'm not sure if implantation happens this late after....
Thanks!