Hello HR,
I am a licensed cosmetologist and have been for several years. You need to stop having her perm your hair with the product she has been using. She is overprocessing your hair. Their is no way to repair the hair that is already fried other then some protein treatments. And I would HIGHLY recommend that you do a few back to back sooner then later if you want to keep the hair you have. You should also wait a few more weeks then normal in between your perms if you can so that your already fried hair doesn't break or melt off more then it is or may be.
I am a strong believer in that your hair is your biggest accessory and when it doesn't feel or look good it affects you. You need to be happy with the way your hair is turning out and most importantly, like you stated, the health & condition of your hair. Unless you don't care about it breaking or melting off, which it sounds like is pretty close if not already happening. You need to either tell her that she needs to try a different perm for thin chemical process hair OR you need to go to someone else. The best way to get rid of the mess she created, unfortunately, is to cut it off.
Another school of thought is to only have her perm the roots if she has that ability and leave the already over processed part out of the rods. This isn't easy, but is possible.
By the way, your description is pretty accurate for destroyed hair from over chemical processing or using the wrong chemicals.
I hope this helps. You can email me personally if you have anymore questions. I would be more worried about you loosing what hair is left at this point then hurting her feelings.
Stay well,
C.