Stupid Raise or Did I Save a Bet?

[dabluebery]

Played this 5/10 hand last night;

BB with AKo. UTG is LAG preflop but decent after the flop and MP is an unknown.

UTG raises to $10, MP calls, all fold to me in the BB. I reraise to $15, and UTG caps. MP calls, I call.

Flop is AT3 with 2 spades. I bet, UTG raises, MP calls, I reraise, UTG caps, MP calls.

Turn is 6s, third flush card. I bet, UTG folds, MP raises, I reraise, he caps, I fold.

My analysis;
I was scared of the turn card, especially from MP who cold called 2 bets twice. If I'm that paranoid about dropping TPTK to an inferior hand, or I'm not convinced that I'm drawing dead here, then I should have check-raised. I still get a sense of how strong MP is, and if UTG is going to lead out, I'm going to feel comfortable dropping TPTK for two bets when it gets back to me anyway.

That said, the 3-bet saved 1 bet on the [turn / river] and convinced me I was beat. I think check-raising could have saved another bet and still given me the same confidence. Check-calling both streets would only cost me 2 bets total. What do I do here?