Ok, I don't want to start an argument here, but after general information.

Why do you guys endorse co-sleeping?

Seems to me that the problems you're having now, converting them to a cot, would not be happening if they were never 'co-slept'?
I love co-sleeping with DD, it is one of the most beautiful things in the world. Just so special.
BUT DD has never slept well in her cot, in actual fact, she sleeps much better with us, and we sleep better. However i start her off in her cot, with the ultimate goal that she will sleep through the night there, but if she does wake she is more than welcome to join us in bed. She knows that she can have cuddles whenever she wants.
BUT co-sleeping has never played a part for us when it comes to quality and or quantity of sleep in her cot.