My Period Last Month Wasn't Like Others. Since I've Had

My period last month wasn't like others. Since I've had by daughter in January my periods have gone on longer than usual (before I used to get it 4 days and not that heavy, after daughter I bleed 5days heavy and 6th day light then it stops). Except last month i got my period a week early and it only lasted 4 days. The first was spotting, second and third day wasn't heavy bleeding and forth day was just spotting. I've taken 3 hpt that have all come back negative.