Pregnant maybe?

I was so so so so stressed out the lat couple of months with school and work and stuff the last 2 months are a complete blur . My boyfriend and I broke up in April . We had sex at the end of April maybe even the very beginning of May. I was suppose to start my period about 10 days ago and it hasn't started yet . I haven't had a May period . I'm on nexplanom birth control and he came in me but he has been cumming in my for months and never got pregnant . Nexplanon can throw off period and make them weird anyways I just don't know if I should be worried ?