The desire to improve is a valuable asset, and one that can't be taught. If at the tender age of almost 15 you have it, don;t let go! That desire is going to keep you going a long way.
From what I see, you have that "teenager lankiness" that most athletes your age come into at one point or another. Have you grown much since last season? That can often throw your balance off. Many of my students are in the same boat, and often, it's a matter of giving them a chance to "settle in" to the sudden change in size before addressing technique.
In keeping with the many cooks, many ideas theme of this topic, I'd suggest that you'd see an improvement from getting your center of mass further forward and on to the outside ski. That will help you when you're driving the those turns and use the energy of the ski to your advantage instead of muscling the ski around the turns.
A simple drill I'd suggest to help with is the heel lift when doing your turns. Lift the tail of your inside ski, keeping the shovel in the snow. In order to do this, you'll need to keep those knees bent to avoid throwing yourself into the back seat. From here, progress to a javelin turn, to work on that separation. Then finally when you go back to skiing "normally" keep in mind that sensation of keeping your knees bent lower. You'll feel strange at first but you'll get used to that.
But above all, keep shooting video and coming back and posting it. It'll be interesting to see your progress over the year!