pregnant !!?

Latricia
Gave birth to my child nov. 2nd I stopped bleeding dec. 10th for about a month me and my SO had been having unprotected sex .  Haven't bled or anything since dec. is this normal ? I know I'm really fertile during this time . But when did you ladies have your first period after birth !? 
**UPDATE*** took  a 88 cent pregnancy test from Walmart & it came out negative