It's time you hopped that trainer up a bit. It won't cost a penny, and you're ready for it.

Re-rig the aileron's. Almost all trainer's are setup with slow ailerons. That's why yours had a tough time rolling. Move the pushrod connections on the aileron horn in one hole. Fly it and see if it isn't quicker on the ailerons. Now try to roll it.

I very often tune a beginner's trainer's ailerons to not be fast. And after the student is comfortable flying and it's time for them to step up a level, we speed up the ailerons. The trainer not only rolls easier, but handles almost everything with more "authority and accuracy". And they're ready to have a different feel to the airplane to learn. And having a quicker airplane without having to buy another one is a real bargain. And I very often fly my student's trainers around upside down. Haven't seen one yet that wouldn't. But trainers definitely want to right themselves. It's what they're supposed to do. And it's great training to learn inverted flight from a trainer. They help you bigtime when you get confused. A model that's better at inverted will be less apt to help you when you get confused.

Can you loop? Consecutive loops? Immelman? Split S? Hammerhead/stall turn? Stall into a spin?

If you can't do them comfortably, and instantly on command, you're not done with that trainer. She'll do a bunch of stuff, she just needs the ailerons hotted up. And MIGHT need the elevator juiced up a touch. But she's not done with you yet if you can't do those things mentioned. And she's the best to learn them with. I teach all my students those maneuvers while they're also learning to land. It teaches airplane control. Which is actually the point of the whole deal.

BTW, if you can do all those mentioned, then have you snap rolled her yet? Some will, some won't. But you'll learn a lot trying it with the old girl.