How to get stronger nails and keep cuticles back?

I eat healthy, and paint my nails with OPI and revlon nail polish, i use a nail strengthening coat underneath and a clear topcoat. I am a vegetarian, so I cannot eat gelatin, which I know is good for the nails, and I already take calcium pills. However, my nails always chip and fall apart. Also, I push back my cuticles before I paint my nails, and also every morning because they go back. They are very uneven and look weird, but they go back every couple minutes!