whats the appropriate bet sizing?

BB: 208 BB (VPIP: 31.62, PFR: 10.93, 3Bet Preflop: 3.27, Hands: 649)
BTN: 128.5 BB (VPIP: 79.07, PFR: 2.33, 3Bet Preflop: 0.00, Hands: 92)
Hero (SB): 46.5 BB

Hero posts SB 0.5 BB, BB posts BB 1 BB

Pre Flop: (pot: 1.5 BB) Hero has 6h 6c
BTN calls 1 BB, Hero raises to 3 BB, fold, BTN calls 2 BB

Flop : (7 BB, 2 players) Ts 6d Kh
Hero bets 5.5 BB, BTN calls 5.5 BB

Turn : (18 BB, 2 players) Js
Hero bets 10 BB, BTN calls 10 BB

River : (38 BB, 2 players) Ac
Hero bets 15 BB, BTN calls 15 BB

Hero shows 6h 6c (Three of a Kind, Sixes)
(Pre 71%, Flop 98%, Turn 100%)

BTN mucks Kd 2c (One Pair, Kings)
(Pre 29%, Flop 2%, Turn 0%)

Hero wins 64 BB