Junk hand, junk villains, overplayed, undreplayed

[Buckmulligan]

The guy on my left (utg) is a real real lag, something like a 50/18/2 and the guy on my right is also fairly laggy with similar aggression numbers but only a 35% VPIP

Preflop: Hero is BB with 5[img]/images/graemlins/spade.gif[/img], 4[img]/images/graemlins/club.gif[/img].
UTG calls, <font color="#666666">3 folds</font>, Button calls, <font color="#666666">1 folds</font>, Hero checks.

Flop: (3.33 SB) 9[img]/images/graemlins/heart.gif[/img], 9[img]/images/graemlins/spade.gif[/img], 5[img]/images/graemlins/heart.gif[/img] <font color="#0000FF">(3 players)</font>
<font color="#CC3333">Hero bets</font>, <font color="#CC3333">UTG raises</font>, Button calls, <font color="#CC3333">Hero 3-bets</font>, UTG calls, Button calls.

Turn: (6.17 BB) 7[img]/images/graemlins/diamond.gif[/img] <font color="#0000FF">(3 players)</font>
<font color="#CC3333">Hero bets</font>, UTG folds, Button calls.

River: (8.17 BB) 7[img]/images/graemlins/club.gif[/img] <font color="#0000FF">(2 players)</font>
Hero checks button checks

I'm not quite sure whether or not I overkilled the flop with a three bet. I believed that I probably had the best hand and hadto protect it. Plus, villain on my right is capable of capping with all kinds of draws which might get this heads up.

I think my check on the end is just terrible. Does anyone else believe that betting this river is imperative?