I would say she's doing great!...don't know how many other non-working group breeds can say (or bark

) that they've done some serious bite work and lived to tell about it!! Most of the working dog breeds (and even some from working lines

) can't do as much!
JMHO: If I was to work your girl, I would really work on building her confidence and not challenge her. I would start by fast moving, no-brainer prey work and bungee (really fun for them). Then when she's absolutely CRAZY about the sleeve and tug I would tease-tease-tease and then do a few run-backs with lots of noise and excitement. Also throw in some on-the-ground bite work where she's on the sleeve and I fall on the ground with her on the sleeve (on my back...belly...side) and let her just RIP it off my arm. Here she has the opportunity to really beat me without me threatening her too much.
After some sessions like this (again, AFTER she's nuts for the sleeve/tug on the bungee) I would listen for the bark and posture I would expect to come after her confidence is 110%!! Deep, assertive bark and just straining to get to me. Once, and only once I see this, would I start TINY threats. If I see her flatten out, I would quickly bring her up with prey and a quick win.
Another technique we've used to build confidence (after ALL of the above is accomplished) is to be hidden in the bush, then you bring out the dog on leash and I start crashing around in there...she can't really see me but knows it's not nice. She should start barking hard and when released fight through the bush to fight the hidden monster! Her confidence will soar through the roof if she builds up the nerve to do it (hence the baby steps to get there!). She'll come back with the sleeve in her mouth to you with a surprised look as if "did you see that thing...and I ripped its arm off!!".
Working in defence is VERY dangerous and you walk a thin line. Very few dogs are built to handle this stress over and over again...and VERY few helpers can work a dog in defence over and over successfully.
Only you know your dog and how much she can handle...don't baby her but be fair based on what she brings to the table.
And have FUN
