Two Colors + Shatter

Lately I have some problems with my nails: they won't grow. They break and exfoliate no matter what I do :-(.

I have chosen these colors for short nails:

Alix Avien - White Shatter

S-he Stylezone - Nr. 204

Miss Maya - Nr. 41

I have tried strengthening my nails with Vitamin A, Vitamin B and Castor oil but unfortunately non of these work.  

How do you strengthen your nails?