Boosting on Nexplanon??

My stomach only seems to be getting bigger but why? I can’t possibly be pregnant if all of the tests are negative. Can anyone really tell the difference between having a bump or just being plain bloated. I’ve also been feeling nauseous the past week and I just don’t know what to do. So, is there a difference between being bloated and possibly benign pregnant?

P.S : I have also been on my “period” for the whole month of December and it’s still going, so this could really mean that I’m not, right? It varies from dark brown to bright red