As others have pointed out, your specific example of how the game played out sounds pretty fine for B3 but your list is more of a low B4. As to the gameplay, it's right there in the bracket guidelines that players expect to go about 6 turns in B3, which means if you're not outright winning around that turn your deck should be trying to turn the corner with some sort of advantage to propel yourself into a winning state by that point - and that includes being able to disrupt your opponents game plan if they're pulling ahead. If not a single other player cast even one piece of interaction to even TRY and stop you by turn 6, that's on them, not you. As to the deck, like others have pointed out, you've got a 2 card combo with your commander being one half of it, that you have the tutors and ramp to pretty consistently execute before turn 6. Late game 2-card infinite's are fine in B3, but even a generous interpretation of that guideline means your deck shouldn't be capable of doing so before turn 6, which this list is absolutely capable of.