Hitting that limit had extremely explosive and agonizing consequences, and was something you’d prefer to never experience again, thank you very much. Hell, you don’t even want to know how apocalyptic that might be in your current state. But like a muscle, your upper limit could be increased through training. Which is precisely what you did, putting yourself through a monstrous regimen just about every time you left Storm Island for “work”, training like crazy until you could safely handle alicorn-tier magic. And then training even more past that. Helps that you managed to pick up a few extra tricks during those sessions that let you fight even smarter!