Doh! Missed value bet again

[gol4pro]

I have a lot of trouble making value bets with just top pair TK or 2 pair in big pots. Usually, 2/3 of my stack is in, and then I check behind on the river.

50$ NL, 50$ stacks.

I have A [img]/images/graemlins/club.gif[/img]K [img]/images/graemlins/club.gif[/img] on button, and raise to 5$ after a couple limpers (I'd like to take it preflop here)

BB cold calls, and my limping friends fold.

pot 10$
flop A [img]/images/graemlins/spade.gif[/img]J [img]/images/graemlins/spade.gif[/img]3 [img]/images/graemlins/heart.gif[/img]
-- he checks, I bet 8$, he calls VERY quickly.

At this point, I just kinda knew. AQ was his hand.

Turn 2 [img]/images/graemlins/heart.gif[/img]
-- He checks, I bet 19, he calls

River 3 [img]/images/graemlins/spade.gif[/img]
-- he checks, I have 20$ left... I need to grow some balls, and check.

Someone shoot me.

By the way, he had AQo.