yeah, of course you pivot. whoever told you not to is a fucking idiot. just don't lean (too much)... in that case you'll leave yourself off balance. also, for fighting a taller person, you WANT to get low.... get low to get inside to take away their power. Mike Tyson fought taller oponents his whole career. He didn't do it by boxing them from the outside. I said this in aother thread... combos more than two punches are pretty impractical. How many times have you seen someone land a clean 1-2-3-4? Mitts don't hit back and oponents move. If you can land a good right hand, you won't need to get off the next shot instantly. Come back with another right if you want.

watch floyd.
[youtube=425,350]5Q0ot6kJC84[/youtube]

now, how many pretty, clean textbook combos do you see? Very few. He throws combos, but they're improvised, and they certainly aren't a clean 1-2-3-4 like you'd see him do on mitts. He throws them based on what the situation calls for. some punches are looping, some straight, some are even slaps... watch at 2:10. 4 right hands in a row. How many times do you see a trainer say, "gimme 4 right hands." Never.

where did you train, at a kids Karate dojo? Forget what those idiots told you. you've also been told good things and do it the way YOU like to. After all these years, you surely have developed your own style. If you like to pivot, don't change it.