Apologies if you’ve already done this, but here are some very high level tips from someone who has bumped into the same issue, but with another instrument.
You’ve already spent a lot of time on this, so you probably are better than you think, but you don’t understand what you know. Or, you don’t know what the “next step” is and you’re comparing yourself to people who have already figured this out and play beautifully (after a warmup and multiple takes).
Playing an instrument is about the fundamentals. You need to figure out what your fundamentals are (strumming? chords? runs? arpeggios?) and practice those simply, regularly. For example, start off each practice with a run through two-octave scales, every note, and play against a metronome. Then, strum I-IV-V progressions for at least the common keys (you can probably skip D#, although this IS practice).
It will probably take you a fair amount of time to do this at first.
Then, if you feel that you’re a beginner, have a beginner song that you play, start to finish, against a metronome.
That’s it. That’s your practice. After that point, you can look at new songs, play favorites, experiment with that capo or slide, whatever. But that’s the beginnings of your practice.
You can mix it up by trying to make the actual practice more musical or interesting. Sometimes, finding a good practice song or etude can work wonders for getting around some mental or physical hurdle, and simply taking a book and opening it up is not a very “fun” way to play music, in my experience, unless you’re already good and looking for a “how to” for that one single song.