I also move forward towards fetal position when there is a big spook or I'm not comfortable. Anyways, I'll try to post a video this evening.
Lower heels will not prevent you from leaning forward. I tend to lean forward a lot - it is my preference in riding - and a lower heel doesn't prevent me from doing so. Lots of folks ride in a forward seat with very low heels...my heels are 55, so they don't bend the way some people's do!
If you want to be more upright in the saddle, you will probably have to force yourself. It will feel like you are leaning back, but a picture would show you are not. In a western saddle, I've ended up holding the horn and feeling like I'm lounging back while trotting, only to have pictures show I was upright at the time. When you sit more upright, you will also need more movement in your lower back to move with the horse.[/QUOTE]