What's fascinating about a grow is that I think most people worry, at the early stages, that their plants aren't growing fast enough... but please don't worry about that so early! Your grow looks GREAT for 2 weeks - seriously! Pick anyone's diary of any strain and go look at their Week 2 - you're not going to see plants that are 18" tall and bushy!! Yes, cannabis grows quickly - and THIS, my friend, IS growing quickly!! In another couple of weeks, you'll wonder what you had been so worried about, trust me...
Good luck and have patience!