I know someone said to diffuse right away to eliminate frizz but for me, that has the opposite effect.

I need to put in my product then let my hair air dry for at least 30 minutes (longer if possible) then I diffuse for like, 2 minutes, literally for some volume. I have to do this no matter what products I use or I get horrible frizz and no curl definition at all, yet I cannot skip the diffusing part of it or my hair is too flat on top.

Try that and see if doesn't help some, since I see that you tried diffusing right away and got a halo of frizz..

Good Luck!
HG:
Winter - Aura Naturelle Gel/virgin coconut oil
Summer - Dep Sport Gel or Biosilk Rock Hard Gelee/almond oil on ends only
GVP Conditioning Balm or Curly Hair Solutions Silk Leave in as leave-ins depending on weather. Coconut oil before/after coloring grays.
2b/c mix waves/curls - coarse, frizz prone, med. thick, porous, at-home color, protein sensitive but I still need it sometimes, glycerin-sensitive (I think) in high humidity.