There was absolutely no way you were bluffing out the underfull in this hand. One thing about bluffing, it's often very difficult to make someone fold a hand that seemed invincible @ one point in the hand, like 5-4 on a T-4-4 rainbow flop. If you actually had KQ, he would've paid you off on the river every time.

I think you could've bet the flop, you have position, and it was checked to you, a T44 flop misses a lot of hands. Still, your flop check is ok.

Your turn call is fine.

Check the river. I think even a pair of tens might call a river all-in from you. Why would you bet 15k into a 15k pot if you had Queens full?