Confusing Hand

[webgator]

No reads on the table and I've only been here for a few hands.

Party Poker 0.5/1 Hold'em (7 handed) converter

Preflop: Hero is Button with Q[img]/images/graemlins/diamond.gif[/img], Q[img]/images/graemlins/club.gif[/img]. MP1 posts a blind of $0.5.
<font color="#666666">1 fold</font>, MP1 (poster) checks, MP2 calls, <font color="#666666">1 fold</font>, <font color="#CC3333">Hero raises</font>, SB calls, BB calls, MP1 calls, MP2 calls.

Flop: (10 SB) 4[img]/images/graemlins/heart.gif[/img], J[img]/images/graemlins/diamond.gif[/img], J[img]/images/graemlins/club.gif[/img] <font color="#0000FF">(5 players)</font>
SB checks, BB checks, MP1 checks, MP2 checks, <font color="#CC3333">Hero bets</font>, SB folds, BB folds, MP1 calls, MP2 calls.

Turn: (6.50 BB) A[img]/images/graemlins/diamond.gif[/img] <font color="#0000FF">(3 players)</font>
MP1 checks, <font color="#CC3333">MP2 bets</font>, Hero calls, MP1 folds.

River: (8.50 BB) 7[img]/images/graemlins/club.gif[/img] <font color="#0000FF">(2 players)</font>
<font color="#CC3333">MP2 bets</font>, Hero calls.

Final Pot: 10.50 BB

I know my preflop and flop play are good, from there is where I am lost.

My thought was to re-raise the MP2's turn raise, but I was still worried about trip J's, yet still confused if he had trips why he didn't bet the flop. Same with the river.