Perhaps take a week off of the bike, and look for other exercises to fill in.
It is hard to say about float. Your SPD pedals had a little.. The SPD-SL allow using wedges and precise adjustment of angles.
Or, speedplay pedals are supposed to have lots of float.
A little float might help your legs move to their natural position. No float lets you force them into the optimal position.
Also, "flats" would allow you to push down without pulling up.
The "knee" is a complex mixture of bones, cartilage, tendons, and muscle. Try to pay attention to where it is hurting as that may also influence your decisions of how to work with it.
Also, does it hurt walking? Swelling?