The way i stand when i jab without stepping my backfoot doesn't move instead of having your right foot pivot in a clockwise direction try and get your front foot to do that. Just like your squishing out a cigarette butt on the floor. i find this helps me turn my whole body around so im more side on ( leaving a smaller target for him to hit ) and lets my jab get its full extended reach.
If that was a bit confusing tell me and i'll coem on a bit later and try make ti easier to understand