Villains an unknown, hes 0/0 over 13 hands

$0.01/$0.02 No Limit Holdem
8 Players
Hand Conversion Powered by weaktight.com

Stacks:
UTG ($6.17)
UTG+1 ($4.92)
Hero ($2)
MP2 ($1)
CO ($2.39)
BTN ($0.86)
SB ($2.02)
BB ($2.28)

Pre-Flop: ($0.03, 8 players) Hero is MP1
UTG raises to $0.08 ($6.09), 1 fold, Hero calls $0.08 ($1.92), 4 folds, BB calls $0.06 ($2.20)

maybe 3b here just cuz im in fairly early position too...but he hasnt played a hand since he sat down and id be pretty lost if he did just about anything in response to it.

Flop: ($0.25, 3 players)
BB checks ($2.20), UTG bets $0.18 ($5.91), Hero calls $0.18 ($1.74), BB folds ($2.20)

sizing is about 2/3, board is dry, im somewhat worried about BB calling behind but i feel calling is best just to keep the hands hes bluffing with at a max. I also figure if villain has like 5 combos of flush draws max, and his range is mainly AK, AQ, AJ, TT+. The weaker hands somewhat discoutned since hes kinda tight it seems

Turn: ($0.61, 2 players)
UTG bets $0.42 ($5.49), Hero calls $0.42 ($1.32)

nothings changed really. keep worse in still?

River: ($1.45, 2 players)
UTG goes all-in $5.49 ($0.00), $1.32 to Hero ($1.32)?

at this point, i start doubting myself. is he really shoving on a double paired board now after a flush comes in? I know villains dont think really hard about our ranges...but even most 2nl donks would think that i have alot of flushes in my range and 4x right? idk, it seems like it he very clearly just told me that hes either 3 barrel bluffing or has a hand strong enough that he doesnt care about this board.