First match your biggest problem seemed to be GnW's biggest downside, which is getting in. D3's ftilt outspaces you, and his aerials aren't half bad either. I'm not really sure what to do in this case, other than try and bait him to approach.
I'd also recommend counterpicking to a stage like RC or Brinstar, if they're legal. (Not sure how D3 does on these stages, so disregard this if he's good there.) Otherwise, go to something like Battlefield for the platforms to help you get in.
Also, second match you had him at +200% and were going for dthrow tech chases, which worked out in the end. Might've been better to go for the throw to kill itself (No idea when throws kill, especially on D3), or just for juggling otherwise
Edit: Turns out his throws basically never kill, even at 300%