Are you:
-watching your replays to identify common patterns and mistakes
-sharing replays online or with friends and ask them for help
-asking people who beat you how they did it, what did they see etc
-not being predictable, thus changing playstyles and attack patterns mid game
-practicing your inputs / ATs
-playing frequently enough
---actively playing your best during play sessins (read: TRAINING)
---not tired / fatigued during
-familiar with all the characters
-knowledgeable on the matchups (will my CS go through his aura sphere?)
-being on offense when its time to attack and being on defense when time to defend
-have any objective metric on how well you are playing / improving
Just because you don't feel like you aren't improving, doesn't necessarily mean you aren't; everyone else may be improving as well (indeed, they are) so you may not notice it. Also, awkward, weird, or fluid, doesn't matter. What matters is the stocks. I don't know how you can be fluid and unpredictable at the same time. If you feel weird with Samus, it means you don't have control over her, and need to focus on the fundamentals. Pick a move or technique, and focus on that. Go to FG and use only 1 or 2 moves etc and try to win. You will quickly learn the limits of that particular move / technique.
Also, if you focus too much on how well you are doing, you could be undermining your goal. Stress is a big killer of ability, just look at people at their first tournament. Try to relax and have fun, and not worry about what the opponent thinks about you, how well you are in relation to others, etc. Just focus on being Samus, and doing whatever it is you can to rack up those percents. And never give up, even if you are down a game, or a stock, or 100%. You can't die if you don't get hit. Just take each second of the game as if it were like the opening of the match.
And yes, be prepared to lose. Often. Especially if you make it to Anther's or tournaments. There is only so much Samus can do, unless you are a superhuman demigod.