My little boy is 4 months and when at home (not car or pram) I feed to sleep then let him just nap on me. I would rather he slept in his cot but when I put him in there, he doesn't settle. If I put him down after he's fallen asleep on me, he either wakes or only naps for up to 45 mins. He can sleep for a few hours if he's on me. Any advice to break this habit?