I wouldn't worry about it too much at this point. A couple more lessons and you will have the feel for it much better. The good thing is, you're not jumping infront of your horse, which is not only a hard habit to break, but it can be extremely dangerous. I usually set ground poles one stride before and after my fences, I sit up straight, place my weight in my heels and when my horse steps over the pole on the take-off side give a slight squeeze with my legs and let my body fold over the fence with my horse, with my bottom still centered in or just slightly above the seat of my saddle. If you ever find yourself feeling "left behind" just let your reins slip so you don't hit your horse in the mouth.