Hi Julie,
I think these are sweet photos. And while a reflector or fill flash would have been helpful, I think that you might be being a bit harsh on yourself. I have found that we are our own worst critics. Most people don't mind a small amount of shadow - or heck, even a child being eaten by their equine neighbor.
I particularly like the last photo. I think the emphasis is on your children and not the horse. The horse - just being there - adds something to a very cute photo!
-JM