DD also doesn't sleep so great in her RNP. She did the first few nights and we thought it was the answer to our prayers (she also has reflux). But now we're lucky is we get an hour of peace when she's in it now. After about an hour she starts grunting like crazy (I think it's a combination of the reflux and her having to poop) and I think she wakes herself up with the grunting. I think the issues is more with the having to poop as whenever I pick her up there will be a small explosion in the diaper area (haha!) and then she calms down. She hates to sleep lying down though because of the reflux.
Not sure if this is helpful...just wanted to let you know you're not alone. GL! I hope you get some sleep! (I feel your pain...by the time I feed LO, change her and then pump, the cycle starts all over. What I wouldn't give for 2 or more consecutive hours of sleep!).