I think something that would help you is adjusting your warmup.
My suggestion soul be working on those things while your warming up. If you have a snatch day, do some tall snatches to work on that speed (same thing with cleans). There are a couple of drills for the jerk that may help you, such as jerk balances or drops (the names of the exercises differ from region to region, but I'll explain).
The first drill you can do is with either a PVC pipe or the bar. Simply press the weight to a height a little higher than you'd normally find it after you finish your jerk drive. Ensure it's not forward of you and in the right position (using a bar would work well because you're shoulders will fatigue rapidly if the bar is too forward). From there, you're going to push yourself under the bar like you would in a jerk. You should foucs on powerfully pushing yourself under and your feet work during this time. As you feel more comfortable, decrease the starting height of the bar. Often times, I find myself starting with the bar on my shoulders and finishing in a jerk, almost like a snatch drop. It helps me get solid feet positioning and work on dipping my back knee to get lower in a jerk.
The other exercise you can do begins with you in a little less than normal split position with the bar on your shoulders. Dip the back knee while ensuring your torso remains upright. Move the head out of the way and drive back up, simulating a jerk drive. The bar will leave your shoulders and give you an opportunity to push under the bar and extend that lead foot a little more out. This helps you feel out proper positioning as well.
I hope those make sense. There are others involving bands and such, but I think you should give those a shot before you go that route. These exercises work very well. The band drills are a little cumbersome to get ready and you need some heavy fixture to tie them down to; on top of the fact that you might be a lone lifter, it can get a little dicey if you don't have someone there with you.
Javier A. Sanjuan
Olympus Barbell Club
Dear God, please help me lift heavy and be awesome. Thanks. Amen.