Hi Sashbash, I have 3b hair and have the same problem. I hate when my hair falls flat. I think it's low to medium porosity and oils can weigh my hair down.
I think my hair turned out pretty voluminous with this combination of products: Kinky Curly Knot Today and Giovanni Hair Styling Foam Natural Mousse.
Use any light conditioner or KCKT, let sit in your hair for 5-10 minutes in the shower. But if your hair has build up (which can weigh it down) you can try Kinky Curly Come Clean prior to conditioning. Rinse it out, let the hair dry in a t-shirt for a few minutes so that it is no longer soaking wet. After that, apply enough KCKT to coat the hair and get out any tangles with your fingers or wide tooth comb. Then apply to Giovanni natural mousse and comb through to ensure even distribution. Scrunch curls, holding a few seconds on each small section of hair. Let air dry. This is how my hair came out using these 2 products - see pics:
I also like ISO Bouncy Curl products but they don't define my hair much.