How do I get healthy hair?

I have a haircut that used to be a shaved mohawk but is now about an inch and a half long. The top of my head is about 4-5 inches long, 4a in the front and 4b in the back although the front doesn't really show much of a curl pattern. My short sides are 4b and 4c. I have been natural for almost two years now and I'm at a stagnant point where my hair is not showing any difference. I have searched for protective styles to leave my hair hair alone because I tend to play with my hair a lot, however, my hair is too short for most styles and too long for others. I apologize for the long message but I am very desperate for advice. Thank you!