Re: small toenails
The nail plate cells are 'born' in the Matrix. You can see the leading edge of the matrix in your fingernails - it is the white half-moon at the base of the nail that we call the Lunula. The longer the Matrix, the longer the nail bed. If the matrix is narrow, the nails will be narrow. There is nothing you can do about this as it is genetic.
As for the nail growing upwards (ski-jump nails), this is also genetic. Mine do this, my parents do this and my sisters do this. The nail bed will follow the shape of the underlying fingertip (or toe tip) bone. If the bone is straight, the nail will grow straight; if it curved downward, the nail will curve downward, if it ski-jumps, the nail will grow upward.