Idk what to do. Maybe I’m crazy but

I’ve been freaking out to the max and I’m not sure why. I haven’t had sex since mid August?? And I’ve had two periods since both on time and all that. (A day early too but idk if that matters) Only thing is that they seemed a bit lighter than normal. I still bled, needed tampons,still had cramps, some clots occasionally (sorry tmi). I noticed that blood was only on one side of the tampon (sorry again) but idk if that’s normal or not. I’ve been really worried that I still could be pregnant. I’ve taken 2 pregnancy tests. One mid September & one today and both negative. But I’ve read that in some woman hcg just doesn’t show up??? I have no pregnancy symptoms except I have some small amounts of pain in my lower sides but I just started my fertile window so I’m guessing it’s that?????? Do y’all think I’m just overreacting??? I don’t want to be pregnant :/