I Usually Recieve My Period At The End Of The

I usually recieve my period at the end of the month. This month i recieved it on the 18th which was very bright but then the next day the flow was way lighter but still bright red. By the next day it turned to a very light pink/brownish tint like when im about to finish my period. After the 3rd day it completely stopped. Throughout this whole time i did eat alot and gained 5 pounds. No back pains, nausea, tender breast none of it. I took a pregnancy test yesteray and came up negative. Can i still be pregnant?