Trimming a stubborn angst ridden cat's claws

I adopted my first cat ever earlier this year. DMS F 2 Y/O. She had a history of abuse and neglect. It was a rough start the first month. She had been returned to the humane society twice already. The last time was for behavioral issues. I took a chance because I'm all about the patron saint of misfits. I was patient with her, gave her space, and let her come out of her shell to me rather than force her to come out. Fast forward I have the most darling, stubborn, bull headed, personality filled love of my life. She's very codependent, and has become my shadow and even protects me when I'm peeing. (Which is such a relief)!

Literally she's my dream cat. She'a loving in her way and shows she loves me through purrs, biscuit making, and never letting my thigh be cat less no matter where im sitting or lying. The only complaint I have is that she is an uncompromising ass who does the exact opposite of what I want her to do a lot of then time. I feel like I have a teenaged daughter! She absolutely will not let me brush her teeth or trim her nails. I took her to a groomer who assured me she's "licensed and experienced with all types of cats". 45 minutes into a two hour appointment I was called back early to find the groomer looked like she was in a war zone and was told that we weren't welcome back. My vet tried the same speech even though I warned them she was a stubborn when they were drawing labs for tests. We were sent home with a bottle of Gabapentine and a rescheduled appointment because I could hear my little innocent looking cat give them hell in the back. Which even with the Gabapentin, apparently she made them earn their pay.

Sorry, mostly venting, but hoping someone could help me with some suggestions on where to go from here. She refuses to use scratching posts of any kind. I've even tried the cat nip rub down that was suggested. I'm out of ideas on how to get these super sharp, super long nails that get caught on anything fabric clipped down without it literally being a scene from slasher flick.

If you're wondering. I secretly used a Gaba pill left over from the vet visit to try to chill her out enough to let me do it. Spoiler, I think my neighbors were considering calling the kitty police because I was obviously torturing her from the horrible shrill sounds she was making along with fighting me for her very life!! Spoiler again, the Gaba isn't doing anything except making her extra cuddly and stoned looking.