nl4 second barrel !

iPoker - $0.04 NL (6 max) - Holdem - 4 players
Hand converted by PokerTracker 4

BB: 60 BB (VPIP: 28.57, PFR: 23.81, 3Bet Preflop: 17.65, Hands: 44)
CO: 114.25 BB (VPIP: 20.90, PFR: 16.88, 3Bet Preflop: 6.30, Hands: 880)
Hero (BTN): 114.5 BB
SB: 50.5 BB (VPIP: 20.38, PFR: 15.92, 3Bet Preflop: 1.89, Hands: 163)

SB posts SB 0.5 BB, BB posts BB 1 BB

Pre Flop: (pot: 1.5 BB) Hero has 8♠ J♠

fold, Hero raises to 2 BB, fold, BB calls 1 BB

Flop: (4.5 BB, 2 players) Q♦ 3♥ 2♦ BB checks, Hero bets 3 BB, BB calls 3 BB

Turn%s: (10.5 BB, 2 players) T♣ BB checks, Hero checks

River%s: (10.5 BB, 2 players) T♦ BB bets 7.25 BB, fold

iPoker - $0.04 NL (6 max) - Holdem - 5 players
Hand converted by PokerTracker 4

Hero (CO): 103.75 BB
BTN: 48.5 BB (VPIP: 20.38, PFR: 15.92, 3Bet Preflop: 1.89, Hands: 163)
SB: 104 BB (VPIP: 20.90, PFR: 16.88, 3Bet Preflop: 6.30, Hands: 880)
BB: 95 BB (VPIP: 26.38, PFR: 22.46, 3Bet Preflop: 5.32, Hands: 339)
UTG: 23 BB (VPIP: 21.88, PFR: 10.94, 3Bet Preflop: 7.69, Hands: 66)

SB posts SB 0.5 BB, BB posts BB 1 BB

Pre Flop: (pot: 1.5 BB) Hero has J♠ 9♠

fold, Hero raises to 3 BB, BTN calls 3 BB, fold, fold

Flop: (7.5 BB, 2 players) 8♥ K♣ 3♠ Hero bets 5.25 BB, BTN calls 5.25 BB

Turn%s: (18 BB, 2 players) 2♦ Hero bets 12.5 BB, BTN calls 12.5 BB

River%s: (43 BB, 2 players) 5♣ Hero checks, BTN bets 21.5 BB, fold

i dont know when i have to fire a second barrel !!
i think i loose lot of money when i check the turn after cbet
what do you think should i do for this leak ??
and how to study it ?
thanks