I had this feeling too. Then I realised a lot about my own play last May. The thing was I was playing too much on auto pilot. When I realised this, I wrote a long post in my regional smash group about it, and they should expect me to rise in skill. I was right. Now when I think through every decision, I feel I can adapt to my opponents' plays. I also get rid of most habits this way. I feel I've reached a higher level, and tournament placings reflects this.
I don't know how consciously you play, but this really helped me.
Another thing is to try to experiment with other styles. Watch IHaveSpaceBalls' matches and get inspired to play a faster, flashier Samus, or watch Duck and HugS to get inspired to play a more cautious, defensive Samus. It's really helpful to learn different styles, because in the end, it's always good to know all aspects of your character.
I spent a long time trying to find a character I liked, that suits me. If you feel Samus isn't the right for you, experiment with other characters! After all, different characters teach you different parts of the game. I believe playing Fox will improve your overall techskill, Sheik will improve your tech chase ability, and Falcon will improve your reading ability.