I understand your frustrations as I have shared many of them. I am a 31 year old student pilot that start training last year. I am based out of a Maryland airport in the SFRA.
First, I wouldn't put too much stock in the numbers of hours. You'll probably find a lot of folks that want to brag about soloing at x hours and getting their license with only the bare minimum required. Last I checked, the FAA didn't give out bonuses for low hour achievements.
That being said, you do want to at least see improvement as you progress, even if its incremental. If the improvement isn't there, then I would strongly consider another instructor.
It took me a long time to get my landings down and if I go a couple of weeks without flying I still need one or two to get them back up to par. For me, I was over thinking the landings. When I switched to start tricking myself into thinking that I would just overfly the run at final approach speed, I found my landings to greatly improve.
Second, I think it is perfectly reasonable to have self doubt. That demonstrates how seriously you are taking your learning. This is a lot of information to process and learn and if it was easy, everyone would be a pilot. Don't let the self doubt consume you though. Think about all the things you've learned since your discovery flight and the progress you've made. The road is long but don't discount the strides you've made.
We're in the same area so if you want to send me a message, I'd be happy to grab a beer or coffee and talk training.