I have never had nails because they flake off and are sometimes broken right down to the quick and they often bleed. I am at a loss, too. I use creams and oils and always apply hand cream. I take vitamin D and B12. I buff them and file them carefully with a glass file if they ever get long enough.
They are better in the summer but come 1 September ( that would be 1 March for you I suppose) they all start breaking off and by Christmas they are back to a bleeding mess.
I have spent loads on various treatments, strengtheners, clear varnishes, powders, creams and gadgets but it's the same every year.
The vitamin D has worked, but only on my hair which has become thicker, stronger and curlier since I started using it.