so he is already down to only nursing at night? did i read this correctly? would he maybe understand the concept of timing? ie "okay, you cna nurse but only until mommy counts to 15" (or whatever random number) depending on how you feel , you cna count slowly or a bit faster to get to the end result. is daddy able to help at night?
also, regarding the ptl, as long as your midwife or doc hasn't put you on pelvic rest, nursing should be fine. the uterine contractions from bf are less intense than those from an orgasm. also stufdes have shown that mothers who nurse through pregnancy have a tolerance to oxytocin(ie the uterus doesn't react as much to it, sicne it is used to the small amounts released).
congrats on your pregnancy