Backdoor draw, fold or call

[testaaja]

Table was loose & passive pf. So my question is: Isn't it correct to fold this flop or just go to the river. Not fold the turn right? If I see the turn I need to see the river for 1 bet because the pot is pretty big. I don't really like the way I called and then folded on turn. Any help appreciated. Thanks!
FTR converter on zerodivide.cx

Preflop: Hero is MP2 with 9[img]/images/graemlins/diamond.gif[/img], Q[img]/images/graemlins/diamond.gif[/img].
UTG calls, <font color="#666666">2 folds</font>, Hero calls, MP3 calls, CO calls, Button calls, SB completes, BB checks.

Flop: (7 SB) 5[img]/images/graemlins/spade.gif[/img], A[img]/images/graemlins/club.gif[/img], 3[img]/images/graemlins/diamond.gif[/img] <font color="#0000FF">(7 players)</font>
SB checks, BB checks, UTG checks, Hero checks, <font color="#CC3333">MP3 bets</font>, CO folds, Button calls, SB folds, BB folds, UTG calls, Hero calls.

Turn: (5.50 BB) 6[img]/images/graemlins/diamond.gif[/img] <font color="#0000FF">(4 players)</font>
UTG checks, Hero checks, <font color="#CC3333">MP3 bets</font>, Button calls, UTG calls, Hero folds.

River: (8.50 BB) A[img]/images/graemlins/diamond.gif[/img] <font color="#0000FF">(3 players)</font>
UTG checks, <font color="#CC3333">MP3 bets</font>, <font color="#CC3333">Button raises</font>, UTG folds, <font color="#CC3333">MP3 3-bets</font>, Button calls.

Final Pot: 14.50 BB