Have you tried doing it every day? It may cut down on ingrowns which can cause bumps, and condition the skin to better be used to it. I will admit that I shave mine every single day, but I've never had problems with bumps. If it keeps up, you could try something like Bikini Zone, which helps with shaving irritation, or a good alpha hydroxy acid product- that's what I use when I have irritation on my legs from riding.