First I like that you are smiling a lot. It gives the impression that you had some good funk that day on your off speed pitches. Hitting your spots and having fun are the most important things to be successful at your current level. Don't lose that.
Energy toward the plate is generated through two main mechanisms: Linear drive to the plate and rotation of the shoulders. Your feeling of needing to stride out longer is your body's recognition that you could develop more linear energy. However, you don't want to just stride out with an open leg. You want to develop your stride by getting your front hip leading your forward movement with your head just behind your center line (google Herhiser drill). Initiating your stride should feel like it starts from inside your posting hip (not your posting knee) While you are striding out your hips should remain closed. You do this by striding out with the side of your foot toward the catcher. (or even leading with your heel slightly)
Once your stride foot makes contact you will begin to rotate your shoulders. This will start with your stride leg firming up (starting to straighten or extend). Next your torso will rotate to face the plate and then decelerate causing your arm to whip around while being driven by the shoulder.
Generally, if you get the early phase of stride right the throwing part sort of takes care of itself.
So for now, you want to work on leading with your hips while keeping your head slightly behind your center line. Striding with your hips closed for as long as you naturally can and taking your chest to the mitt. I would begin this work from the stretch to eliminate change of direction issues from the wind up.
If you post a question in the mechanics area you'll get more info.