A common problem I see with peoples leg drive for overhead pressing is their heels coming off the floor as they dip and them tipping forward, this leads to them pressing the bar in front of them rather than overhead.
One way of fixing this is to widen your stance, point your toes out more to the side and make sure your knees track over your feet when you dip. This will allow you to stay more upright and keep the weight on your heels, it also stops you from tipping forward.