It sounds to me like all the flat-ironing etc. has left your hair very dry and craving for moisture. How long have you been flat-ironing etc. your hair for? Does it feel at all thinner than it used to?
There are a few things you can do for your hair-
1, If you do want to continue to use heated tools on your hair, it is ESSENTIAL that you use a decent heat-protectant on it.
2. You could try going CG. This is a method where you don't use shampoo at all, or much less of it. However, it doesn't work for everyone. I would certainly try it for your hair though.