My period was due sometime between Monday and Thursday 5/26

I started bleeding heavy on Saturday and today it's let up alot like I can wear a thin pad for 2 hour and maybe a couple drops are on it. I took 2 pregnancy test before the bleeding and they was negative.

I had something similar before I have a subchronic hemorrhage( a pocket of blood that burst) and I carried my 2nd son full term. Or could this be Breakthrough bleeding?