well, OK, so, my hair's fine and porous, so YMMV, but the one thing both me and my coarse 3B mom found straightening was the alaffia beautiful curls wavy-to-curly gel. It makes both of us shiny and smooth, but with less curl. In my case, that means "flat with a giant flip at the ends," not a good look, but her 3b hair resolves to something that looks more like 2c with 3a bangs.
You also might try, when your hair's wet, post-leave-in, combing through it then not scrunching after. That will leave mine less unruly. But I don't have a strong wave pattern.
You don't say how short your hair is, but if I want mine straight (it's chin length) I'll kind of--reverse plop, I guess. I comb it straight back while wet, tie my flour sack around it, and go about my business for 20 or 30 minutes, then let it go and dry as usual. That straightens it pretty well also.
2a/2b, fine and thin
cleansing: BS/ACV rinse weekly
PT: Gelatin PT
Conditioner: Desert Essences fragrance-free
Styling: LOTD Aloe