Horses need more hay than a lot of people think. If you're feeding grass hay and the bales weigh about 50-65 lbs, then yes, she should be getting 1/2 a bale a day. Fall/winter pasture grass does not have much nutritional content, so you need to supplement with hay. A horse should be getting 2-3.5% of their ideal body weight in hay every day, so for a 1,000 lb horse, that's 20-35 lbs of hay.
My hay isn't that great either, so I supplement it with alfalfa pellets, flax meal, and a good vit/min supplement. I would use this diet even if I fed really good hay, just with less alfalfa pellets
Love the cristmas picture, too cute!