That's good you can get abit of sleep co sleeping - co sleeping doesn't work for us :-(
I don't have the same problem anymore but ur post title sounded just like me - feel like I've tried everything and don't know what to do anymore. Im at my wits end. My problem is that feeding to sleep doesn't work alot anymore and nothing else really works either. I'm up roughly every 2 hrs aswel.
Dd is 7.5 mths now but she used to always do the same thing as your lo. Either wake as soon as I delatch or when she was put in the cot. What I did for months was feed her to sleep at night and then have her sleep on me for 30-60 mins roughly and then transfer when she was in a really deep sleep.
For day sleeps she sleeps on me.
Have you tried the pantley dance? I started doing that at about 5 months and that worked pretty good for us for awhile. Basically what I would do is feed her on the lounge til she just falls asleep, then stand and start rocking/walking round her room. I delatch her whilst rocking so that she's got the movement to distract her and she stays asleep. She protested sometimes but because she's already really sleepy the rocking would normally get her back asleep. Then I would alternate rocking/moving around with standing completely still. No pattern with timing, I just keep making the standing still parts longer each time. Then I would place her in the cot.
Hope that makes sense- I'm pretty tired right now 😜