Hand History

Villain: unknown but seems like fish because he is short stack.

Flop: I think C-bet is fine since I have backdoor FD and runner runner straight.
Turn: I made FD. now, is it time to double barrel or just check-back and hope another heart comes on the river?
I doubt that I do have fold equity at this time. If villain has ace, I doubt that I can make him to fold his ace. Also, I don't know what to do if blank card:not heart at this time, come on the river. If King comes on the river, I would check back and see show down but what about others? triple barrel?

what if I am OOP? I think OOP, I think bet is better than c/f or c/c