It's hard to tell much from one picture, but here's what I noticed:
Your heels are down nicely, but it looks like your toes are pointed out, therefore losing your knee contact. Try to keep your toes pointed straight forward, and even if that causes you to lose a little drop in your heel that's okay...you've got some room to spare on that. Make sure your thumbs are pointed up (it's hard to tell from this picture), and try to get a little more bend in your elbow, this will bring your hands up a little and will feel funny at first!
I also want to mention that you have a pretty good line from shoulder to hip to heel! So overall, your position is pretty good...looks like you're maybe very slightly tipped forward in this...but it's barely noticeable and could be you just moving with the horse's motion.
Now, if you're riding hunter/jumper I might be wrong on the leg critique...I know most hunter/jumpers ride with toes out and heels way way way down.
A horse is the projection of peoples' views about themselves--strong, powerful, beautiful--and it has the capability of giving us escape from our mundane existance.