Hello Barb!
It can be frustrating to find that you are not progressing despite all the effort. Firstly of course you may just not be ready to get the full wrap. And that is OK. Just keep trying. It could be a question of technique. Remember the definition of insanity: doing the same thing over and over again and expecting different results? Perhaps it is time to look at it a little differently. 
Try this:
Don’t “squat” low in set-up.
When you sit ‘low’ in the hips, scoot your butt behind you but keep the chest up as high as you can. You are trying to sit low in your hips, but your feet have to feel really firm and evenly weighted. To break it down further, you are trying to keep your center of gravity over your feet. Many people sit low but drop the chest forward over their knees. Please avoid this at all costs as you will pay the price in the pose spending your whole time neither being able to get an effective wrap, nor be able to balance easily. You will spend the whole time trying to get your chest right back to where it should have started. So, sit hips low, chest high arching the spine to keep the chest over your hips.
If your head bobs up when you wrap your legs then you know you have sat too low in set-up. In other words, once you have ‘sat’ down, your head should stay still at the same level when you wrap the legs. Then it moves vertically down as you sit lower and lower.
Wrap the leg where it wraps.
No matter how you slice it, you can only wrap the legs so that they twine. In fact being asked to lift the leg as high as possible seems to go against what you are trying to achieve. If you are sitting in a chair when you wrap your legs, you will start by crossing them with knees in proximity. You now have to do that while you are standing.
Think of your lower leg as a ‘chair’
Sometimes I find it clicks with a student to tell them to push down with the top leg on the bottom one. Use the bottom leg as support and seat the top one heavily on it. Pressing down, you may feel the belly of your hamstring muscles shift and spread a bit as you exert this downward force. Or it could just provide you with the visualization that you need that gives you better balance as you sneak your toes around.
Chest up high to start, slide the back down the ‘wall’
I guarantee that if you start with your chest up high (when setting up with hips low and feet firm) that when you start to move your hips down, your chest will be in the optimal position. You will be able to sit lower, your wrap and balance will be better.
Kind regards
Gabrielle 
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