I'm sorry I have no advice but all I can suggest is go with ur heart and u will know what to do
Maybe see ur doctor is ur concerned maybe just a bloody test to see if u might be ovulating without AF
If ur not ready to give up that bf and co-sleeping time then maybe ur not ready but its totally a personal decision and I commend u for being able to bf its a wonderful thing (I was unable to due to my daughter being prem)
I hope u work it out and all the best I am sure u will have another bundle of joy as soon as ur ready