No sex but skipped period?

So I’m a virgin but I know that fingering can (in a super small amount of cases) cause pregnancy. I’m not on birth control because it messes my stomach up. My bf and I are usually as careful as possible with everything (he and I both always wear underwear and he always wears a condom even though we aren’t having sex. He will sometimes cum in the condom but this shouldn’t be on his hands when he puts them in me).

Even with all of our carefulness, I’m 4 days late on my 21 day period. I’m basically always regular. There are extenuating circumstances that could be the cause. I just moved home from being abroad in the Uk for 6 months, had bad jet lag and such from that, introduced my bf to my family for the first time, and am going back to my home university that I don’t like.

Even though I know it’s probably just these things, I’m really worried. I have very sore breasts but no other real symptoms. I was very horny (a normal PMS symptom for me) when I expected to be PMSing but then no flow.