Keep fighting the good fight!
I also had several moments where I thought Thor would never get it. I even started a thread titled "Untrainable?".
For me, the key was total, total vigilence. We had about two weeks where I really didn't do anything but watch him. As Nancy suggests, I put him in his crate every few hours, and when I took him out, I took him straight to his pad and said, "Potty." If he didn't go, I put him back in the crate for ~15 minutes, and then tried again. We had two marathon sessions where he stayed in his create for OVER 24 HOURS! But when he finally went, it seemed to click for him.
I also took about a month where he was only allowed in my living room (which pretty much meant that's where I always was too). Then I added half of my hallway. A week later with no accidents, the entire hallway. Another week, the bathroom. Etc. It felt like an eternity, but I think overall it was only about two months, and it's sooooooooo nice to take his training for granted now.
Thor was about two years old when I got him, and he'd previously been allowed to roam free in his owner's office building, so he had tons of experience going indoors. And even he got it. Your dog can too!
Whatever your method, it boils down to vigilence. If you cannot watch her with BOTH eyes, she must be in her restricted area (crate/xpen). If she's sneaking off to pee, that's a sign that she needs to be watched more closely / has too much freedom. As I said, the extreme, don't-let-them-out-of-your-sight-for-even-one-second attention lasted for several weeks, and then I could relax a little more, while still keeping most of my apartment off limits.