Help?

Hi so I had protected sex with my boyfriend about three weeks ago just after my period finished (about the 11th of April) . He didn’t finish in the condom and I had swallowed the sperm (sorry if a tad TMI). I’ve been having cramps like usual about a week before my period was meant to start and all the other symptoms that go with that. I took a pregnancy test on Thursday (28th of April) just to put my mind at ease and it came back negative. I am currently two days late on my period and I don’t know what’s going on.

Side note I am b12 and vitamin D deficient and saw the doctor and lead nurse today and they said that my really strong cramps and headaches are nothing to do with my b12 injections and that it’s just pre menstrual

Please help because I’m panicking like hell