questions on every street, backdooring a straight

I'm playing a live 30/60 game, 8 handed at the moment. Thinking LAGish player raises HJ, loose player coldcalls in the CO, TAG calls on the button. I look down at 99 in the SB and decide I have an equity edge and 3bet. BB folds, everyone else calls.

Flop comes down Q86r. I bet, LAG raises, loosey coldcalls, TAG folds, I call with the intention of reevaluating on the turn.

Turn is 7, completing the rainbow. I donk, LAG raises, loosey calls, I call.

River is a 5, I check. LAG bets, loosey raises, I overcall, LAG makes it 3, loosey reraises, there's a fivebet cap, I vomit and call.

Thoughts on any/all streets? I think the I should have checked the turn, in retrospect, because the 7 makes a lot of twopair type hands that loosey could have...my donk was not good, I feel. The river is kind of interesting as well, imho