First of all, you've done things that work for 90% of all leopard geckos... maybe 99%. There are a few though that are very high strung. I have two drop-dead gorgeous super-hypo subadults (no spotting on head of body, barely any on the tail, and one is so bright he should have a radiation symbol on his forehead). Both are from the same father. Both panic so completely when they see people that it would be funny if it weren't kind of sad. In their case I think its genetic. Since my business/hobby is called "friendlylizard.com", and my focus is on providing easy to handle friendly leos, I wouldn't even hang onto them if they weren't so enthralling.
That doesn't mean they won't tame down. It does mean it will be a far greater challenge and accomplishment than for your run of the mill leopard gecko. They may never be as relaxed around people as some are. In fact, if you want a buddy to hang around on your shoulder for long periods of time this one may never get there. This won't be a leo you can hand to your friends so they can feel how soft their little bellies are. It will calm down enough to be handled though if you are very, very patient.
If you are dedicated to taming this leopard gecko, and I think you are, it can be done. Back off for a couple of weeks .. do nothing but feed, clean, and change her water. When you clean her substrate, gently place her in a temporary container with sides that aren't completely transparent (I use ziplock brand .. they come in red & green for the holidays and the critters seem to feel more secure inside). Change her then gently return her.
Figure out baby steps, small things, and keep one up until she is used to it. This might be coming into the room without turning the light on and watching from 5 feet away (rather than walking right in the tank) or simply putting low music on so she is able to tolerate some changes no matter how small. You're working on building up her tolerance, and the first steps will require the most patience.
I am sorry to hear that regular (every day) handling has not helped. Often it does, but it can take weeks to see advancement (and it helps to keep a journal of how its going ... sometimes you think there's no progress at all yet you can open the cage without her freaking out .. or feed her without wondering if a reptile can actually die of fright.
Your leo is going to take persistance, determination, patience, and creativity on your part. You will have to observe and find those small areas where she can progress on your own. Please do post and let us know when she makes those little breakthroughs!
Andrea A.
p.s. It really is ok and some people believe preferable to let them stay wild. While its better to have one used to handling in case they need to be examined for injuries etc, or in case they need to go to the vet, many herps don't even have the potential for taming as leos do. And since they can live for 20 years.... well, there's always time.