Played my first real money session today, and although it started well (went $10 up lol), I lost it all on a biggy, just wanna see how u guys would have played it.

Well sb was 0.25 and bb was 0.5
I was dealt A(s) and K(c) and in late position i raised i tripled the bb.
Got two folds and two calls.

Flop comes, A(d) k (d) 3(d)
FLopped top pairs, but was worried about the flush, all checked.

Turn 6(c), two check, so i raise $1.5 hoping no one has the flush
one call and one check

River 8(s), he checks so i raise $2 he goes all in and i have to call
He shows Q(d) 2(d).

He set a perfect nut flush trap for me, but how would u have played it? wat did i do wrong here?

Cheers guys