hello Ghazala!
From my experience in application procedures etc, I think your NBDE score is decent enough esp with the new format. You should definitely retake your IBT and improve those scores. your GPA is pretty solid and you have work experience in Canada. Generally, schools look for well-rounded candidates. If you still think that improving your NBDE scores will be the only way to get admissions then that is upto you.
best of luck......