first of all, Jim is right. figure out YOUR way, within reason, and stop worrying about if it's right.
secondly, I think it would be a good idea for you to either start doing touch-n-go reps, or completely come off that bar between reps. The sumo was fine, but something wonky is happening when you're resting at the bottom of the conventional. contrary to what some believe, I think you'd have better form throughout the set by using touch n go- forces you to stay tight. or, since you're taking a few seconds between reps anyway, release the bar, stand up, reset feet if need be, pull next rep- this shouldn't take any longer than you're already taking.