I'm really tired. 6 months in and it's regressing to how it was in the beginning

Adopted a lab mix. Gf and I went to a puppy Pilates session and I was absolutely in love with all the puppies there. We caved in and adopted a 1 month old black lab mix.

I'm not gonna lie, there isn't a single day since where I don't question that decision. We dropped a ton of money in a trainer, toys for her. It doesn't matter what we do. We can spend the entire day playing with her, tiring her up. If she's not on her crate, and we take our eyes off her for one second, she starts destroying our shoes, eating food off the counter, biting the cat. It feels like we can't rest for a single second.

The fault is entirely mine, I thought it would be way easier. The people on the rescue house told me it would be easier, that the puppy wouldn't need any training, no special needs. I don't know if they were straight up lying, if they didn't know the dog would turn out to be so rebellious, or if I'm just a bad owner. Either way, I should have researched a bit before adopting.

We're not rehoming her. I think the amount of times I've cried, the nights I didn't sleep, the fights I had with my gf because we were exhausted from her behaviour, will be repaid in time. But now I sincerely feel like giving up, and that she would be way better off with someone who has the experience and/or patience to properly raise her. But I also hope that I can grow from this experience, and that the dog is not as affected as I am from it.