Oh citymonkey
you sound like you're having a really hard time. I'm not convinced this is something us lot on the Internet can really help with. Do you have a bf cafe or similar near you? Are you a member of the NCT? We got a list of local bfc who would come out and see us if we were having feeding issues.
All I can say is that your DS sounds really similar to my DD. We were slightly different in that she was prem and tube then bottle fed expressed milk. But she came home on bottles of expressed milk, fed regularly, kept well etc. Then when she was about six weeks old she seemed to wake up to the world. She learned to bf. But she also behaved very like your DS. She fed from one side only for five mins max (with the exception of evening cluster feeds). She didn't want put down. She wasnt happy being held in a cradle position, she wanted to be lying on my chest. She would be awake for 1-2 hours at a time at night. And didn't sleep for any long stretches of sleep. I think she did have some wind which I wasn't great at bringing up. But when I put her in her Moses basket she often screamed and screamed and I was convinced she had awful wind and I was a bad mum for not bringing it up properly.
I posted on here at the time as I was seriously considering putting her back on bottles as I was connecting the BFing to being unsettled. But in her case I think she had just woken up to the world and wanted the reassuring presence of mummy.
It did pass. Like your DS she was putting on weight well. So I just soldiered on through it, though looking back I'm not sure how I did it. I'm pg with DC2 and am planning on setting up a bedside cot beside my bed so I can sleep with a baby on my chest without fear of rolling over and dropping said baby. Is that maybe an option.
I would advise just doing what is needed to get through just now. Don't worry about the future. My theory is that if you give a baby all the comfort and closeness they need it actually makes them more secure and I don't buy the whole 'rod for your own back' argument. I would co sleep, so that everybody gets the rest they need and your baby gets the comfort he wants/needs
Anecdotally, DD now sleeps all night in her own cot. Though she's going through the 15 month sleep regression so she and I end up in the spare bed in the middle of the night a couple of times a week.
Sorry I do tend to ramble
but I hope some of that was helpful.