NL50 Flopped TPTK and rivered Trips

[wibbo]

PokerStars No-Limit Hold'em, $0.50 BB (6 handed) Poker Stars Converter Tool from FlopTurnRiver.com (Format: ITH Forums)

UTG ($50)
Hero ($59.25)
CO ($49.25)
Button ($187.15)
SB ($50.25)
BB ($48.10)

Preflop: Hero is MP with :9c, :as.
1 fold, Hero raises to $2, 1 fold, Button calls $2, 2 folds.

Flop: ($4.75) :7s, :4d, :9s (2 players)
Hero bets $3.3, Button calls $3.30.

Turn: ($11.35) :2s (2 players)
Hero checks, Button bets $8, Hero calls $8.

River: ($27.35) :9h (2 players)
Hero checks, Button bets $20, Hero calls $20.

Final Pot: $67.35

Villain hat nach 77 Haenden Stats von 24/16/2.4/60.

Line ok? Betsizing?