No AF & no BC... help!

Denisse
My baby was born 11/23/2015, and I breastfeed until 10/2016. I was on DEPO for a year and did go back for my 12/2016 shot.  I still have not been visited by AF, going on 2 years now due to pregnancy and breastfeeding. This month I thought I was getting it but it was only 4 drops worth. 
I had a doctors app last week and she told me to come back at the end of March if AF had not visited. She mentioned my progesteron might be low. She also tested my thyroid, looks normal. 
Any advice??