Certainly not scientific, but my experience:

Nursing my daughter fully - never saw a pacifier or bottle, every hour or so;
my period returned at 6 weeks and was regular from then until I got pregnant
with my son when my daughter was 9 months old.  Both children nursed full
steam ahead and I still got my period at 6 weeks post partum, again.  I had
several arguments with people who said I was not nursing fully - neither
child had any food until 7 months old.  We never owned anykind of artificial
nipple anything...

I am not too over weight (5 lbs) and I did have abundant milk.  I still have
a little milk, 4 years after weaning my son at age 2, daughter ata ge 3.5
(they quit together - after they discussed it!)

I am very interested in the early return of menses while fully bfing.

Sharon Fontaine Terry