late period after protected sex and pregnancy test is negative

I am 18 I had sex for the very first with my boyfriend just after the day my period got over. We had protected sex and even then he never ejaculated inside me. Also, I had late periods before this happened I had 2 day course f progesterone pills and I got my periods , just then I got my periods and as soon as it got over I had sex . I had done my pregnancy test on the 14th day after coitus and it'snegative. Still it's 10 days late from the day I expected my periodsand now I am worried af!