I've seen more serious players put in more bad bets in poker for this reason than almost any other.
You know where you're at. You have a seven-high flush draw. It's definitely behind and needs a diamond.
It will sometimes be near-dead to a larger flush draw, but betting the flop won't tell you that. It's just a risk you assume with small suited cards, and maybe you can escape cheaply if the bigger flush tips his hand. Betting the flop is a mistake, for the reasons I outlined in my earlier reply.
You also bet way too small. If ever a bet might tell you where you're at, it won't be a bet of 1/3 of the pot. With $12 and change in there, you need to bet more like $8 to $10 if at all.
Anyway, on to the turn. I'm gonna say a bet of $16 just to one-up
@DrStrange.