crossedwires, I relate to your OP totally - that was me 9 years ago but he was my first born, so I didn't have the sanity to realise it was not normal (whatever "normal" is ).
I got into the awful situation where ds would not sleep at all, day or night, if he wasn't walked and rocked. Then came the nightmare of actually putting him down to sleep and praying that he would actually stay asleep. He would wake frequently at night and would nap for no more than thirty minutes at a time during the day (you could set your watch to him). He was 8 months old too, but I had long since given up breastfeeding. I think you have done wonders to continue feeding a child who is clearly exhausting you in every way possible.
Anyway, one night I was so tired that I decided I would put him in the cot awake (never done before), just for ten minutes, so I could get a break. I hadn't heard of cc at this point, so I suppose you could say I tried it be accident. Anyway, before the ten minutes were up, he was fast asleep and slept for seven hours solid! The best sleep he had ever had! I never really looked back from this as it became apparent that what he really needed was to go to sleep on his own. Every night from then on, I put him to bed awake and he was asleep within a few minutes. Yes, he cried, but literaly for a few minutes. The longer sleeping pattern continued and he was only waking once in the night at around 4. Within weeks, he had stopped this too and was sleeping around the clock.
He is now a very bright nine year old, who still sleeps very well but is very active during the day. He's in to football, cubs, anything scientific, bike riding and his PS2!
I hope you find your personal solution soon, but just wanted you to know I've been there too. You may be surprised at how quickly the cc works.
Also, re: turning him back on his back. I thought this wasn't necessary once they were old enough to turn by themselves?