We learned our lessons from DD1 and DD2. We have coslept with DD3 from day 1. It took us a few weeks to figure out nursing while laying down. She'll be 10 weeks tomorrow and we're still only doing maybe 2 feedings a night while laying down.
My problem is that she gets some MAJOR spit up when we nurse laying down. Sometimes even an hour later. Any reason why she'd get more gas when nursing laying down? It's compounded by not burping afterwords - but that's kind of the point of nursing laying down, so we don't have to get up and can just drift off to sleep.
I didn't nurse while laying down with DD1 and DD2 until 3 - 4 months. I don't remember this happening with them.