I have the exact same problem!
I know I should think more when I fight, learn how to counter properly and remember my combos. But unfortunately I play MUCH better on autopilot, even against an opponent who knows me well, than when I think. The moment I start thinking my gameplay collapses. I automatically mix things up, anticipate my opponent's moves, etc. when I "autopilot" so I don't use the term to mean mindless repetition. What I mean is I just can't get cerebral about my moves so I can't seem to memorize combos (I can pull them off intuitively, but intuition can only take you so far - I can't do very long combos).
The sad thing is it also works when I play against really pro people, I eventually get used to their playstyle and win even though I STILL haven't learned any decent combos. I know I'm not playing properly but when I autopilot I get positive reinforcement (after a period of losing to someone until I get used to them), when I don't, negative reinforcement. Though if I could get used to playing properly, I know I'd win a lot more.