How to get my old hair back?

I used to have pin straight,silky fine hair.Somehow over the past few years its gotten damaged.I don't use flat irons or cheat shampoos i use very expensive kinda and don't blow dry my hair either.I've repaired my hair recently and my hair is now very nourished but how can i get my hair to be very fine and not so thick and make it extremely silky again.