Knowing the notes better implies (at least what I think Chopincat was saying, correct me if I'm wrong) having the entire piece under your fingers, able to play through the entire piece with little to no mistakes in timing or notes.
While I wouldn't recommend dropping this piece, I think it'd be beneficial to your playing to play some Chopin mazurkas. Go ahead and get the complete set in whatever edition is sturdiest (or cheapest!), then read through them all. They're quite beautiful pieces of music, definitely worth studying.
Try playing this piece as softly as possible, making sure the nail joint (second joint on any finger after the knuckle) doesn't collapse; this will give you a much easier time playing softly. This will help you project volume whilst still maintaining tone; playing forte does not mean banging (which you weren't always doing, but some sections definitely were quite bangy).
Let the phrases breathe, it will sound much more musical.
Also, it's nothing personal. I love the waltz, and you play it fairly well; your D flat major section is one of my favorite renditions of it ever!