river betsize?

iPoker - €0.20 NL FAST (6 max) - Holdem - 6 players
Hand converted by PokerTracker 4

Hero (BB): 152.85 BB
UTG: 169.4 BB (VPIP: 10.00, PFR: 0.00, 3Bet Preflop: 0.00, Hands: 10)
MP: 97.45 BB (VPIP: 20.00, PFR: 12.00, 3Bet Preflop: 0.00, Hands: 26)
CO: 210.3 BB (VPIP: 30.45, PFR: 23.20, 3Bet Preflop: 9.72, Hands: 2,459)
BTN: 49.9 BB (VPIP: 50.00, PFR: 10.00, 3Bet Preflop: 0.00, Hands: 10)
SB: 118.55 BB (VPIP: 25.21, PFR: 18.49, 3Bet Preflop: 6.00, Hands: 122)

SB posts SB 0.5 BB, Hero posts BB 1 BB

Pre Flop: (pot: 1.5 BB) Hero has K♥ 9♥

fold, MP raises to 3 BB, fold, fold, fold, Hero calls 2 BB

Flop: (6.5 BB, 2 players) T♦ 4♥ 9♦
Hero bets 4.55 BB, MP calls 4.55 BB

i thought he will often xbeh this flop , so i plan to donk/call and hope to improve

Turn: (15.6 BB, 2 players) 7♣
Hero bets 10.9 BB, MP calls 10.9 BB

when he just calls i think he isnt that strong as i expect him to fastplay, and 7 doesnt seems to improve him so i barell again

River: (37.4 BB, 2 players) K♣
Hero bets 33.65 BB, MP calls 33.65 BB

and here the main problem is size IMO, i guess this was too isolating, and ofc i would have to fold vs raise , though dunno if i would ingame... but a lot of hands beats me now like KT,JQ , and i beat only KJ,KQ so if im targeting so small sample i should be bet/folding smaller? since KJ+KQ=16combos, and KT+JQ=22combos
i know u might ask that how many QJo or KTo he has in his range, but this is iPoker, they just raise anything pretty ♦ , thought if they had suited only then he KTs+JQs=6c and i have clear valbet , thought not still sure about sizing being used and why use such sizing, so make it clear for me please ♦