It sounds like you are really gently encouraging him to make the transition from cosleeping to being on his own. It's probably not something he's delighted about, but I understand how you must be ready!

If he stays in his bed, am I right in understanding that you go back in? I'd personally hold back from going in to kiss him if he's quietly lying in bed. Persisting with putting him back, without too much fuss or cuddles (ie firmly, but gently, no talking, maybe a quick shh and a pat - unless he's upset), will eventually pay off. As long as you're consistent he will learn that this is the new way of going to bed and will adjust.

That's my suggestion, as unhelpful as it might be! But it really sounds like you already are doing the best thing, you just need to keep going. It will get better and it probably will happen pretty quickly. What a lovely Mummy taking such care of your little boy!