One of the ways I eased into the sidelying position was to sit up and start in the cradle position and then ease down into the bed without detaching the babe. That way we both learned what it should feel like without starting from the latch. After we tried that a couple times, dd was able to latch on like a champ and I know how to hold her and my breast/body. HTH!
Our dd had the same issues with being put into her bassinette in the early days & would only sleep with us; eventually we found out it was due to acid reflux. sleeping on us kept her patially elevated and that helped her a lot. Your baby may not have this problem at all, but just thought I'd bring it up; I would have loved to have known that was a possibility back then.