Badly confused

[Yerma]

Players are a little on the loose-passive side.

So, I have A6o in BB. 2 limpers, SB limps and I check.

Flop is AT9 rb. Checked to last to act who bets. SB folds. I "just" call. Player in between calls.

Turn is 4 rb. Checked to last to act who bets. I call. Player in between folds.

River is a 6. I bet. He raises. I call.

I was confused in a couple of places. What do you think?