Really scared — late period

My period isn’t usually late, but it’s five days late. I had sex twice this past month — but both times there was a condom. The first time it was too painful for me so we couldn’t finish (around Dec 8). The second time (Dec 19) the guy finished early but not in me if I remember (although I can’t be sure — 100% there was a condom, though), and then when we tried again, we weren’t very successful :/

I’m experiencing period symptoms — cramps, lower back pain, and even my acne flared up. That said — no period. I took a pregnancy test on Dec 25, already three days late — negative. On dec 26, I had a previously scheduled doctors appointment where they blood and urine tested me — negative.

With that, it can’t be from the first individual I had relations with, but maybe the second....? (Please don’t judge me for having sex with two guys in a month; I’m in college...)

I’m worried it’s too soon after the possible date of conception to get a reliable result. I cannot get pregnant, and I just don’t see how it’s possible. (We used condoms and I don’t think anyone finished inside me!) That said, why am I experiencing all of these period symptoms?? I’m really scared and confused.