For just 3 years of training you are playing very good tennis. But, you are competing against players who played much much longer with similar intensity. Keep it up and keep working hard but it's time to find some high level instructions and coaching to further your development.
A couple tips. I love the energy on your footwork but it's a little over the top being on the balls of your feet. That wastes energy and reduce solidity on your shots. And you gotta learn weight transfer not just putting your body in the middle of your feet all the time. Try to learn putting your weight on the heels more and only go for the balls of the feet when needed. This will give more stability and solidity for each foot and be able to transfer weight for the benefit of your shots.
Your backhand. The contact point is too low relative to your hands and it's not on the most efficient swing path. Try to lower your hands and lift up the racquet head for the contact point. Swing your hands lower than the ball not level. This should improve solidity and consistency of your backhand.