3 month old sleep problems

So, ever since I had my baby, I allowed him to sleep on my chest to comfort me and himself. I stopped about a month ago but he hates sleeping on his back and so I have to rock him for at least 15 minutes to get him to sleep, then put him in his swing until his next feed at 11pm, and from there, I put him in his crib but he wakes up every 2 hours, almost on the dot, to comfort nurse. I know he's not hungry because he falls asleep within 5 minutes of nursing. I am so tired and have heard so many people say "he should be sleeping 4-6 hours in the night" I have done so much research into sleep training and I don't think we're ready for it. I'm so tired, I just wanna put him on my chest again and sleep.. Any suggestions for helping him sleep on his own? Or just helping him learn how to sleep on his back