Is preflop sizing OK?

What about flop sizing?

Once the flop gets called by the button, are you jamming the turn and if not, what's your sizing?

Poker Stars, $0.10/$0.25 No Limit Hold'em Cash, 6 Players
Poker Tools Powered By Holdem Manager - The Ultimate Poker Software Suite.

BTN: $26.88 (107.5 bb)
SB: $18.20 (72.8 bb)
Hero (BB): $49.77 (199.1 bb)
UTG: $25 (100 bb)
MP: $39.55 (158.2 bb)
CO: $25 (100 bb)

Preflop: Hero is BB with A K
UTG folds, MP calls $0.25, CO calls $0.25, BTN calls $0.25, SB completes, Hero raises to $2, MP calls $1.75, CO calls $1.75, BTN calls $1.75, SB folds

Flop: ($8.25) 9 Q 3 (4 players)
Hero bets $4.25, 2 folds, BTN calls $4.25

Turn: ($16.75) 4 (2 players)