I was in similar shoes to you up until the last six months or so (same age too, haha). I will caveat that by saying that I have ridden pretty consistently since I was sixteen with the exception of a couple of 8-month breaks, but I quit taking lessons towards the end of my last year of college and was largely on my own for the last five years (was riding with a friend, but only a handful of lessons/clinics over that time).
I had a terrible experience psychologically with the trainer that I left in college and once I picked riding back up again afterward, I was pretty much exclusively on greenies with absolutely wrecked confidence. I did buy a horse about five months after I started riding again, but up until this year we were pretty much just puttering around because he had a lot of growing up to do (seeing as I picked him up off the track as a 2yo for $1500), I was still trying to remember how to find the whole thing fun again, and I spent most of my time with a little voice in the back of my head telling me that I was incompetent and not good enough for my horse (thanks, former trainer).
I had the opportunity to reconnect with my childhood trainer (who started me in eventing) and was fortunate enough to move to her barn in January, and it’s been a major adjustment for me. I had (and have) a lot of bad habits to unlearn, in part from my time riding on my own but also from that other trainer. At the beginning I was so frustrated with myself and the fact that I couldn’t do things that I could do as a kid that I had to warn my trainer that it had nothing to do with her if I started crying during a lesson. When we first moved I couldn’t even canter my horse down the long side without losing our lead because of how crooked I was in the tack. Six weeks ago she pointed us at a jump for the first time and I honestly don’t know how I didn’t throw up given how anxious I was.
Last week she sent us through a line of three 5* minimum width skinnies and my horse (who is barely seven and had never seen a skinny before in his life) marched right down it like he’d done it a million times. Afterward she told me to save all of my blooper reel clips for a compare and contrast when we’re running around Intermediate. This weekend we’re doing Fix A Test with most of our barn so that I can clean up the Beginner Novice dressage test before we go to an event this summer. In two weeks we’re going to our first show since we moved. I was joking with my trainer that if we actually do BN this year, I’ll have officially made it back to the skill level of 12yo me, and she just told me that we’re going to do it and in max two years we’ll be running Training.
Coming back to it is hard. It’s really hard. I’m not sure how much me riding before this even helped, to be perfectly honest, because I’ve had to completely retrain my body over the last five months and it’s only in the last few weeks that I’ve actually started to feel good and moderately competent again. Last week is the first time in years that I’ve looked at a fence and not panicked about it. For the first couple of months after we moved I kept track of everything we did in my planner so that I could compare the changes and challenges, and that helped me a lot to see the progress even during weeks when I didn’t have particularly great rides (I definitely recommend this strategy if you’re like me and prone to nitpicking everything). You just have to give your brain and body time to catch up, and try not to be too hard on yourself (though I know that’s challenging when you think about what you used to do).