Compared to most equine study college riders I have seen you are doing an ok job (so which school are you at)? (It is so dark it's hard to see...are you w/o stirrups?) In short you want the same alignment of ear/shoulder/hip/back of heel. (And for both seats that is missing). The difference is you are more upright than you would be for light seat/jumping, chest lifted/upper arms hanging vertically and you have a straight line from elbow to horse's mouth (in walk/canter you still follow the bascule of the gait). In the pix (quite dark) it seems that you have shoved the heels too far down and hence out in front of you (missing the alignment of e/s/h/back of heel). The leather should be vertical, and you feather into the heels not fix the leg so that the heel is out in front). The horse you are riding is perhaps a little low and closed (but this is the fashion of today's riding oftentimes). (BT's comments do not all float my boat.) A big difference for a hunter seat rider is that jumping riders ride with the foot on the inside of the stirrup and slightly turned out. For dressage the foot is place on the outside of the iron, and the rider is slightly closer to parallel (as your conformation allows). The iron is generally just below the ankle bone vs hitting on or slightly above it when the leg just hangs (before mounting just extend the fingers to the top of the leather...and the iron should hit your arm pit)...then do any nuances.

Have fun.