Due date?

Jo
I had my daughter December 4th 2016, I had sex January 7-13th at my postpartum visit (January 19th) I had a negative test....January the 21st I had light spotting once when I wiped (probably implantation bleeding) took a test Friday the 27th and got a very faint positive...I haven't had a period yet when would my due date most likely be???