started my 9month old bull x whipet pup jumping last month or so and I've noticed she doesn't seem as, how do I put it, 'springy' as other dogs I've had. She's around the 21inch mark, and is pretty quick and gets up ok. But as I've been increasing the height she seems to be struggling to clear the fences a little. I've had small dogs in the past that have had no problem clearing same heights as bigger dogs, but this one my heart is in my mouth if she goes over anything with barbed wire. Any ideas on why this could be? Should I leave her mature another couple of months or just let her find her