Boobs changing??

Ok I’m 24, I’ve always had between D and C cup boobs, just changes with my weight usually which is normal. They’ve never been saggy even the slightest bit...until now. I lost a lot of weight the past few months without trying, i have no idea how bc i haven’t been exercising or eating healthy at all or even trying to lose weight, but out of nowhere 40 pounds just like disappeared...I’m currently back to a C cup but the past few days I’ve noticed (maybe I’m crazy) that they are sagging a bit and it looks from like side that my nipples are like curving upwards a little bit...? Idk if that even makes sense but that’s how it looks. Could this mean I’m pregnant?? I’ve gotten two periods, taken 6 tests all negative, but I’ve been nauseous off and on every day too. I figured out i would be around 2-ish month by now if i was so wouldn’t i get a positive test? I don’t sleep well at all and I’ve been really stressed for a couple months now from school and work, and i do struggle with bad anxiety and depression (depression has been much worse than usual all winter too). Is this an early sign of pregnancy and all my tests are wrong?? Or could my random dramatic weight loss have to do with my boobs changing?