No periods

Background: My son is almost 2. I'm still breastfeeding, but only in the morning, before bed, and some weekend naps. I went off birth control around the end of October and had a withdrawal bleed. I haven't had any periods since, and haven't ovulated (I've been tracking my bbt). When I was off birth control to get pregnant with my son, I was having long cycles, generally about the equivalent of skipping every other period.

Could it be normal that its not back yet? At what point do I need to make an appt with my doctor?