Quick answer you cant do a damn thing sorry to say ... i know its not what we as parents like but these little ones have other ideas but it will no doubt alter again.
Maybe snuggling with you in bed will be enough to stay asleep even on the boob so you can have more zzzz before its least nearer to 6am ....and when a little older yes he can get used to playing in cot
Maybe his whole feeding waking routine has altered as they do all the time ... so suggesting you forget what used to happen and prepare for the next version.
and i wouldnt really worry if he gets 2 out of 3 solids in a day he will let you know as he is doing now. but hugs all the same