I am no expert, but I can tell you a few things I see. Your lower leg as well as your heels look lovely, that being said, your lower leg seems rather long (as in your stirrups are long). The jump is not high, so that isn't really a big concern, but it is my personal preference to have a shorter stirrup and a lower leg with more angle while riding cross country. Totally my preference, and your position looks way better than mine, so who am I to talk, right? Your eyes are up, which is fabulous! The only other issue I noticed with your position concerns your elbows. You look like they are pointed out, like wings. Rather than bringing your elbows out during your release, try to keep them closer to your sides.
Now, concerning your horse. He is adorable btw. The way he is squatted on his hocks looks like he was launching at the bank, rather than taking it in stride. It looks like he might have tried to stop or hesitated at the base before he changed his mind and decided to try it anyway. His right hind is totally out of the picture, suggesting he is not taking off squarely with both of his hind legs. He does look very focused and interested in what he is doing, which is always good, though.
I hope this was a helpful critique. Great job for trying cross country on occassion. It is very fun. :)