I have breastfed through two pregnancies. My DS1 didn't take to fm at all! To this day, he still doesn't.
As long as your period has returned, you can still conceive. As for bfg during pregnancy.. well, if you can make love to your hubby.. you can breastfeed.. very similar hormones produced with similar contractions of the uterine wall resulting.
breast milk supply usually does dip the week before your period but should return to normal thereafter if you continue to feed on demand isn't our bodies great?
like i said earlier.. ds1 never ever took fm.. dear daughter took fm at about 18mths cos mother in law intro'd it and she had self weaned cos i got preggy again. ds2 took fm cos he kaypoh follow his jie jie.. sigh.. he's still being bfd now.