You’re getting excellent advice. I spent many many years in your position and when I finally had the money to afford something nice it was so easy to move up to bigger jumps because I always rode anything I could swing a leg over, I rode as much as possible without stirrups and in my 2 point, and I studied all information available to me.
There is such good information available online these days. A clipmyhorse.tv subscription is a little pricey but has endless hours of clinics and horse shows to watch. I believe you get access to a lot of it with just a USEF membership though, so look at the details because that would be cheaper. Watch the every horse mastership clinic on repeat, watch the Beezie Madden flatwork demonstrations from the last several years over and over. The big FEI classes are fun to watch but I find there’s more to learn from watching some lower level open classes, where you can watch, for example, a good pro take a spooky horse around the 1.0m ring. In the junior/ammy classes you can often hear the trainers yelling from the in gate. All free lessons!