Man, mine didn't return until my son was like... um, 22-23 months? I guess he's 33 months now (2 years, 9 months) and I got my period back last year in September. I only got it back when I stopped pumping at work. However, in the UK you have up to a year maternity leave, and I was on maternity leave for 10 months... so I was feeding on demand for that long, and then I was feeding on demand at home but then also still pumping at work (I was still bringing pumped milk for him to his childminder to drink well beyond a year... until he was 20 months probably... because I figured why give him cow milk when I still make human milk? Heh.)
Finally I dropped the pumping at work (it's nice I am allowed to pump at work however long... I got paid for that time, which also helped encouraging me to continue!) and my period returned about a month later!
Although, even now, I am still breastfeeding! So that is I suppose one part of my sway... hope it's helpful?
The same will probably happen with me again next time (my period taking like two years to start again)... maybe!