I don't think the sylvanas on curve was very good. If it made him skip his turn, it'd be great, but with drake on board it was pretty weak plus he had 7 mana left over after that.
You also have shadowflame in hand to take care of the board if it goes too south. Plus sylvanas + shadowflame or poweroverwhelming in hand as well. I see why you made that move but I'm not sure if I would have done the same. I think I would have tapped for another card, maybe played brann because I don't think brann is that important vs druid. Maybe play brann and run the imp into drake so if he uses it to trade it's dead and it's also in range of hellfire.
Lets say you waited a turn for sylvanas, it could have really slowed him down. I think that is sylvanas' best usage. Maybe I'm wrong and you would have gotten flooded, but with the hand you had you could have gotten the board back.
After turn 10 looks like you had it on lock down.
Nothing to really comment on other than that. And maybe it was the right play but just a very weak one.