This might be a bit of a shot in the dark, but I would be tempted to make up the mixture without the tofu, and then add an extra egg to it if it needed it. I think the tofu would add to the protein count, and might add extra moisture and body, but an extra egg, or even just whites, would do it. The texture wouldn't be quite the same. Any reason why you don't want to use the tofu?
I've not tried whey powder yet. As I am lifting weights regularly I need to increase my protein, but not sure if I'll like the whey!!!
If LemonSong is still about (he's hard at work hitting the books) he might have some ideas!