You don't necessarily have to buy in to the GUE/DIR way of doing things to be a good diver.
If you want to use what you have, fine. As far as advanced courses in PADI, a lot of it has to do with how good your instructor is. Some barely cover the materials up to the standards and won't demonstrate good trim, buoyancy, finning techniques, etc. because they don't know much about these things themselves. Then there are some that really are good and can show you things over and above what is required.
You can do a lot of things on your own to start with. First, trim up your gear so you don't have anything hanging or dangling. Clean up hanging consoles, extra long inflator hoses, if you're using splits, lose those and get a pair of paddles since you'll be learning to do heli turns, modfied frog kicks, and backing up.
Find some good mentors that you admire their diving styles.
Work on your buoyancy. If you went through the typical PADI curriculum chances are you might have been overweighted to some degree. Work on getting your weight down to where you can hold a stop at 15 with no air in your BC. Use this as a starting point to know right where the line is for minimal weighting then you can adjust from there.
Work on laying flat and cruising along horizontally.
Also you might want to work on things like mask R&R's, air shares, etc to gain confidence and fluidity. Doing a lot of diving helps, but if all the dives are just benign with no challenges where everything is easy with no problems then they won't do you as much good as a dive where you create a scenario where you can employ some skills training. You need to get a buddy that is willing to do this sort of thing with you. Classes are great but those are a one time thing, what about after that? That's why it's important to do all this stuff on your own.
You can work on all these things with the gear and training you have. If you want to take GUE fundies at some point at least you will have been working on some of these things already.
And if you do have the mindset to start working towards DIR then you will need to get a BP/W at some point. They aren't that much and it will be the last BC you'll ever need.
Anybody if ever seen here on SB who inquires about GUE/DIR or a more advanced style of diving beyond what PADI teaches eventually goes to BP/W anyway, so may as well just do it. Don't get me wrong, I'm not trying to push you into a BP/W, but it sounds like you are already half way there.