100NL: I played it too timidly I think

[TheDespot]

Hero ($77.75) is BB with Kc-Qc

UTG+1 ($118) raises to $4, UTG+2($55.75) calls, folded around to Hero, Hero calls
Flop 4d-Ks-6s (Pot: $12.50)
Hero bets $6.50, UTG+1 calls, UTG+2 calls
Turn 4d-Ks-6s-Qs (Pot: $32)
Hero checks, UTG+1 bets $12, UTG+2 calls, Hero calls
River 4d-Ks-6s-Qs-Jd (Pot: $68)
Hero checks, UTG+1 bets $19, UTG+2 calls, Hero calls

Comments: UTG+1 is a reg who I generally see playing when I scan to play tables but I have rarely played with at a table, UTG+2 is an unknown. I know I have to reload to a full buy-in. I know if I bet the flop I have to bet more, but I made it smallish to see where I was at in terms of getting information for a smaller price, though this obviously lets a draw get a good price. As played, do you like the check-call on the river? Anyone check-raise, bet out, or check-fold? And how do you play the turn here? I fudged this hand up I think and was definitely too passive and left myself in an awkward spot where I didn't really know where I was at, which I do very rarely and I'm kind of annoyed at this one. So how do I fix it up?
One last thing: the reason why I played so cautiously was because of the UTG+2's coldcalls on two consecutive streets. I smelled spades though I wasn't positive.