Period 3 days early and not like normal

My period came three days earlier than expected and it's not like my regular period is, since I had my baby 7 months ago my periods have gotten a little heavier but this period isn't the same it's way lighter. Is it possible my body's still adjusting in some way? Also I had unprotected sex two days before I was supposed to ovulate and am not sure if I could possibly be pregnant.