It bites me in the ass. Stupid bet sizing, letting him see cards cheap?

Full Tilt No-Limit Hold'em, $0.10 BB (8 handed) - Full-Tilt Converter Tool from FlopTurnRiver.com

MP1 ($3.40)
MP2 ($5.73)
CO ($12.70)
Button ($13.22)
SB ($3.50)
BB ($12.53)
UTG ($10)
Hero (UTG+1) ($4.67)

Preflop: Hero is UTG+1 with K, A
1 fold, Hero bets $0.40, 1 fold, MP2 calls $0.40, 4 folds

Flop: ($0.95) 3, A, K (2 players)
Hero bets $0.50, MP2 calls $0.50

Turn: ($1.95) 7 (2 players)
Hero bets $1, MP2 calls $1

River: ($3.95) Q (2 players)
Hero bets $1.90, MP2 calls $1.90

Total pot: $7.75 | Rake: $0.51

Results:
Hero had K, A (two pair, Aces and Kings).
MP2 had Q, Q (three of a kind, Queens).
Outcome: MP2 won $7.24