Hey Suzannah,
The key with this problem is persistance from you. You say it looks like you're making progress by taking your feet away - you probably are. But puppies reset in memory pretty quickly, so you'll just have to stick with it in a repetitive way. She will learn, but you'll have to keep at it for a while.
If she growls back at your partner when he tries this, be sure to tell her no immediately. You don't want to encourage her to "back talk" now, as this may set you up for problems with her challenging your authority in the future.
You might try putting her in time out when she starts chewing? Immediately put her in a small, dark, quiet room by herself (bathrooms usually suit pups) and leave her there until she calms down. Tell her "no" as soon as she starts biting, then put her in time out. You have to do this every single time she bites, otherwise it won't work as well.
Again, the key with this training is REPETITION haha. Puppies need the same lesson drilled into them a few times before they get the picture on training

I hope this makes sense, let us know how you get on!