To be completely honest, there is little feedback we can provide without some gameplay from your end. It's very difficult to diagnose a condition when there are no symptoms to reference.
If you can record some matches and/or upload replay(s), it would be quite a bit easier for us to suggest next steps and potential areas of improvement.
Don't give up though. While it may certainly be difficult to improve, surrounding yourself with the right community, listening to feedback, and playing more in general will undoubtedly improve your performance.