Period early last month late this month

Casey
So I had my tubes tied in 2012 after my third baby in Feb I ended up pregnant again and had my right tube surgically removed due to ectopic pregnancy. My husband and I want another baby now but we know that it's probably not ever going to happen. Now for my question. I was ten days early for my period last month it was like a period but not as heavy as I usually get. This month I was supposed to start on the 15th my periods have always been regular what could be going on. I took a test and it was negative. Thank you ladies.