I'm trying to cut down on my shampooing routine, but my hair always go flat after a day or two.

After a shower I'm a 3a, but during the week my curl reduces to a 2b and frizz bonanza begins. Sometimes even a 2a during summer.

I've been doing this for a while and I can go up to a week without my hair getting greasy, but I thought my curls would stay when my hair got used to it. I only comb my hair when it's dry, right before i shampoo it, meaning once a week-ish.

Does anyone know what I need to do to make them stay?