6.Bd3 is dangerous because without your bishop Black will be able to control all the light squares on the kingside. When Black can cover g6 he can play ...h5 and Nh6-f5 and no one will be able able to kick the knight.
I think Black can get away with 15....b6 and 16...Kb7. It's a cool idea though.
Was unnecessary blunder on his part, but it was fun to force myself to be on the offense.