Help me please!

So my period came on the 14th & went off the 19th i had sex the 19th & my bf came in me the same night now idk if i have a 28 day cycle or a 35 day cycle I've been told the 28 day cycle ovulates on day 14 but my cycle comes that day & a 35 day cycle ovulates on day 21 so ur fertile days are 19 20 21 i need help anyone i really don't know if I'm a 28 or 35 day cycle person my doctor told me yesterday i could be gettin pregnant because I'm very fertile after my period& that I'm ovulating early so do any one have answers for me plz