The best advice we can give you is to find a experienced trainer to work with.  Just squeezing may not cut it at first, you may need to build the pressure to get results.  The best way to learn what to do is to watch some one do it in person and ask questions of.

I think even a few sessions (at least) with an experienced person would a) shorten your training time b)avoid mistakes, which can be difficult to undo c)prevent getting dumped, which you understandably aren't keen on doing. Getting advice piecemeal on a forum like this may not be very helpful since we can't see the horse, how you are doing things, how she's reacting etc moment by moment. it's not just what to do, but timing. Horses often come up with  solutions we hadn't thought of e.g." I'll just stand here and kick my foot if she asks anything of me", and as soon as we don't have a pretty quick solution for redirection, they know they've got our number. A horse is always learning, they just aren't necessarily learning what you hoped they would or what you thought you were teaching. You might think you are teaching how to move off nicely, meanwhile Princess is learning how to avoid work, or she might just be confused.

Ask in your local tack shops/fram stores/Co-ops and vet offices, they're great places to start your search and usually know of at least one trainer to start with.  I do NOT recommend takng this horse out of a controlled area (round pen, arena, small fenced area) until you know for sure that you have control in steering and brakes- in order to have either of those you must first have forward motion though.  

Where are you located?  Maybe someone on her is close to you and knows of a trainer that can help.

I have begun riding lesson with the goal of rebuilding my confidence through real skill.  I want to do it right. One problem that has cropped up recently is that this mare has become super head/ear shy.  She freaks totally out if I reach for her head. She does okay if I start at the withers and work my way up. I have to move slow.  It has made her very difficult to handle on the ground.  Any pressure on the halter and she goes verticle. We have avoided rearing, but its just a matter of time.  She throws her nose in the air, but crowds me. So far I have been reinforcing the personal space by making her back up.

It's pretty difficult to help long distance especially when we can't see what she or you are doing second by second. Your thought to find someone to work with consistently is a good one, finding the right someone is the trick, right? My guy behaved somewhat like your mare when I first got him, wouldn't give to pressure, flinging up his head, wouldn't tie, etc. I just took it slow, put very little or no pressure on the line, made no big deal when he flinched, just worked with him as far as he would go gently. If I was leading and he stopped, I stopped, or just wandered one direction or the other, but paid no attention, like I just meant to do that (lol), then carried on when he relaxed a little, and so on. I didn't do the backing up thing because he already seemed to have a tendency to balk, and back up, given an excuse, and I wanted forward (except when he forged).  So I tried to keep it all as low key as possible because getting him even a little more worked up wasn't helping him get his brain in gear. It is a slow process, I'm sure experts can whip these guys into shape in no time. but I got the result I wanted in the end. Now he will walk nicely with a lead, or with no lead, a rope around his neck or a halter. In his case it just really seemed like an anxiety issue related to tying and saddling, so the whole process just had to be nice and easy, every day. No dramatics, no high handedness, and he gets it now. He will come to me when I show him the halter and even lower his head (sort of) to let me put in on. but it all takes time.