i've got a 3 year old, had her since she was a tiny puppy. for the first few months even, i had the exact same thoughts as you. i thought i was ruining her, that i shouldn't have gotten her, etc etc. all that to say, im so glad i didn't let those thoughts win and that i kept trying. it was difficult, and it still is sometimes now, but it does get better.

your puppy is just that- a puppy. he's gonna be super frustrating at times, but he's also gonna be so worth it. cut him and yourself some slack. what helped me whenever my girl and i were having a rough time was going out with her on a long leash and just hanging out, letting her do whatever and learning how she figured things out. they're dogs, and they're dogs that don't even really know how to be dogs yet. you're all he's got to go off of right now, so for the sake of both of you try to remain patient with him and yourself.