Inside Leg

So we've covered how I need to work on inside bend with Kachina and let go of my outside rein. In conjunction with that, I need to be able to use my inside leg, because if I have a loose outside rein, and I'm asking for inside bend, I need a way to keep Kachina out and not turn on tiny circles. However, I've discovered another hole in our training: I can't apply inside leg without outside rein or Kachina will take it as an aid to go faster.

Kachina used to think that using any bit of leg in any situation meant faster. I did a lot of lateral work with her to get her to realize that one leg on meant that I wanted some part of her to go sideways rather than forward. We start every warmup with exercises to isolate and move her hip, ribcage and shoulder in both directions. We've done leg yields at walk and trot. Basically, I thought we had this issue solved.

Unfortunately, I guess all of past my leg yielding work was done while using outside rein (because I apparently always use outside rein). I don't need to put much pressure on the outside rein, but if it's there at least slightly, I can get Kachina to yield sideways with my inside leg as much as I want and she will stay relaxed and in the same rhythm. However, if I let go of my outside rein while I put on my inside leg, we get an instant trot instead.

In the grand scheme of things, I don't need to go around with a floppy outside rein. However, this hole in what we can do shows a gap in Kachina's understanding, and that needs to be addressed. Also, right now I need to exaggerate release of my outside rein so that I stop relying on it and so I can keep the aid for inside bend clear.

I need some advice though: How do I avoid teaching Kachina to blow through her outside shoulder if I am asking for lateral movement without my outside rein? Any suggestions?

P.S. Sorry for lack of media, I need to rope someone into take pictures of me riding someday soon.