There is something small you can take to help your hair and nails grow. It's called Folic Acid, they sell it at CVS Pharmacy or Walgreens. It's not expensive and you get over 200 tablets and they're very very small. Maximum strength is 800 mcg. Take one a day every day with a meal and after two weeks you'll notice hair and nail growth that will look much healthier.
Also, you may not be noticing your hair growing because you trim it every two weeks. You're cutting off all the new growth. Try trimming every 2 months.
I used to flat iron my hair every day or every other day and every time I grew two inches it broke off eventually. In May I decided to leave my hair alone and be curly and the growth is through the roof. I noticed that flat irons made my hair thinner and the roots and ends and more dry. Now I just shampoo, condition, and put a leave in conditioner in my hair and let it air dry curly. If you want to straighten do the same thing but with this extra step: mix a quarter size of leave-in conditoner with a straightening serum. Rub it together with your hands and evenly put it through your hair, use a wide-tooth comb to even it out then blow dry and style.
But you'll be much happier natural with good moisturizers to keep those curls happy. I talked to a lot of different people about their curly hair and what helps it fall better like straight hair and the answer is always the cut. Layers help the curls fall better and look less poofy.
And whoever cuts your hair make sure they cut it when it is dry and curly; you'll keep more length that way because they'll be thinking of your length in curl terms and not straight terms. It will look better curly when its cut in it's curly state.