No confidence in my shot?

I shoot the single, the double I get in and I stop. As much as I drill I always stop short instead of drive through when I train live. One tourney I got the front facelock could have cradled him but instead I wanted to see what he'd do and ended with a ac separation. I'm 236 maybe I should forget the shots and clinch more?

 Im no expert but The way it was explained to me to help this:

1.  Learn to knee slide through and crack down on the far knee if your in on a double and can keep both legs. or;

2. Switch off to a single and keep driving through back to the feet.

3. If your stuck and cant generate any forward movement tripod up and work back to the feet

Its important to shoot then drive through back to your feet to finish if possible.  Dont just hang around underneath on your knees.   Realize its a lot of hard work and requires some conditioning and explosivemness to pull off. 

World champion Jordan Burroughs whole game revolves around the above techniques.  Check him out, amazing:

you just gotta fine the variation that works for you personally im a smaller guy at about 170 but the single legged low level work best for me and i see more big guys utilize it more then smaller. you shoot for their near leg, head inside and put ur shoulder on their shin and push back. most people find it harder to sprawl against it because of the pressure on the knee and if u get thhe leg and get stuck its easy to elevate the single or to transition to the double.