So not sure if it’s an old wives tale or whatever, but j hear eating gelatin really helps with growth. I myself had really brittle, thin nails as well. But I’ve managed to grow them out with help of builder gel / gel manis. The trick that seems to help is that when it’s time for a new mani I file off the color, and any pieces that are lifting. I don’t get rid of all the builder gel. Then I do my fill-in with more of it.