That actually sounds reasonable. I'm guessing that you still might not be bracing as hard as possible.
Personally I don't think there should be a difference in bracing with or without a belt. Pushing out against a belt is a cue that many people use but don't forget that the purpose is to recruit as many muscle fibers as possible and fire them all as hard as possible because they're all working to compress the air in your stomach (transverse abs, obliques, the 6 pack abs, everything) to provide stability.
As you're sitting down right now, take a moment to take a breath and brace like what you would normally do. Poke all around your mid section from the front, side and back. Does it feel soft? Is there any give? Now try again by taking a huge breath and flexing your mid section so hard that it feels like steel armor that even swords can't pierce. That's what bracing should feel like.
I made the mistake early on of pushing out against the belt by blowing up my stomach like a balloon. I thought that was tight until I learned how to brace properly without a belt. Adding a belt shouldn't change your mechanics or the approach for creating tension. It only increases pressure because your abs are confined to a tighter space. Since the volume decreases, the pressure increases to compensate (assuming you took in the same amount of air).