Your technique is really good, especially for a 14 year old- like damn. While you can always improve technique, I don’t think that is what you should focus on right now. Go to museums, read books, watch film, follow artists online to see what else is out there. See what you like and what you don’t. Find out what art moves you and ask yourself why? Then go and try to creative artwork from within yourself, and not just copies of work you have seen. The more you challenge yourself the better you will be.
Like I said- your technique is pretty outstanding, and more developed than then most at your age. So why not focus on what it means to be an artist. If you want more guidance on this read “Letters to a young poet” by Rainer Maria Rilke. I prefer this translation but that’s just me personally. Letters to A Young Pier