I get really flakey nails that break easily too, which is really disappointing. I use a nail polish from L'Oreal (called Ceramide Resist). Its a clear polish which is meant to strength and care for your nails. But also makes them look nice, shiny and smooth. Its definately worth trying it out. I think its a little pricey thou but if it works maybe its worth the money.
my nails were also like yours and i was an awful nail biter but i then had acrylic nails on for 8 weeks and had them taken off yesterday, they look fantastic and are much stronger and longer. during the last 8 weeks ive also been putting this special oil on, i dont know what its called but you can probably find out if you go to a nail bar and ask. stregthenung stuff does work but i find it difficult as i always have red nail varnish on and it tends to smudge it.