Exactly as said by Pighardia you should go to Skellige asap.Been playing the last few days still enjoying the game and I'm still on on novigrad moping up question marks, think I've done the majority of side quests. I am level 19 and can kill stuff quite easily in their early 20s. I am wearing enhanced Griffen gear which seems pretty good. I can leave for skellige but I'm trying to 100% the maps as when I finish this game I won't come back to it as my game time is limited and I won't ever get to play other games. Probably won't finish this game till Christmas.