Can anyone tell me what grade I would be in guitar?

Well, if grades existed, I’d call that close to grade A I guess. However music is a universal language that crosses all kinds of boundaries between people. Notice that artists have a “style” that is their own and songwriters, well they are the root of the tree. A well written song can bring emotions out of people that they didn’t know they had anymore and think about things they have forgotten about. (just a philosophy of mine, hope you don’t mind) Your playing skills are obviously well on the way, I encourage you to be creative. It’s a great feeling to write a song and other people love it !! (It’s also great to be able to play like our heros too isn’t it)

People don’t tend to worry about grades much when it comes to the guitar. I’d say, just by what you wrote, that you’d be around grade 4-5. But that’s assuming that you are using the right hand positions and techniques, which most self-taught people don’t. If you have done all of the technique practice and exercises, finger exercises etc.. scales etc, then you’d be grade 4-5. But if you can only play chords, read tab, and basic things like hammer ons etc then I’d say you are about grade 2-3.