Still no AF

Ashy • I have two amazing boys, born 05-30-2015 and 04-07-2017 and we are going to have another baby in December 2018😍😋
My little man turned 8 months old 2 days ago and I am dying for another... I want him to be two by the time the other one would be born and I still haven't had any sign of Af coming back... He doesn't feed as much anymore because I work graveyard ALOT and I am not ALLOWED to pump for over 8 hours which Is another story  but  I don't know how to get my fertility back.. I love him but I also want more 
So my question is how do I get it back without having to stop he is so attached to me I think it would break his heart if I decided to stop he isn't ready yet..