I posted something very similar in the 3b forum a few weeks ago... my hair looks very similar to yours. I can get volume by using products with glycerin, but then I get the frizzies along with the volume! If I just leave it alone, I get really nice spirals... but flat roots.

I've tried clipping, plopping, etc, but I have to choose only one: Either definition or volume. I can't seem to have both.
3a/b fine, high porosity, medium density. Mod- CG

Sulfate-free Shampoo: SheaMoisture Curl and Shine shampoo with Epsom salts.
Co-wash: TRESemme Naturals,
Leave in: TN Radiant volume, KCKT, YTC pampering conditioner
Summer styler: LA Looks Spiked Gel(summer only)
Seal: Argan Oil/Macademia Oil
Winter styler: KCCC, AIF, Beyond the Zone Noodlehead curling creme(not CG)
DT: GVPCB, coconut oil
PT: GVP Hair Reconstructor
Embracing my curls.