With modern larger knee pads and butterfly technique, you need open landing areas. I don't see any way to get that without going knee-to-calf with any straps, even the elastic. Any strap behind the knee across is going to cause binding and lack of rotation.
If you are missing the landing gear, you can get smaller knee pads which will allow you to get closer to the front of the pad and on to the gear. I would normally recommend Passau, but since you are smaller, they are going to be too big and cause you the same problems. I would look into either the Bauer 1S or Warrior Ritual X Pro retail guards. Both have a pretty slim profile and are still protective. I have the Sr version of the Ritual X, and I really like it. If it were better cushioned in the landing area, I woud be wearing them over my Passau's. I think the Pro version will address that and also be more protective. You may also consider the strapping system that Monster Hockey sells that goes around your calf. It replaces the knee strap, so you get a much more open knee cradle, but it still keeps your leg in place and the pad in control.