I would watch her for ulcers. The behavior you describe of eating a little, then stopping and looking around, then eating more, then stopping was CLASSIC ulcer behavior for my gelding and believe me, he had no interest in what goes on in the barn, but he would look out his stall door or window and it would "seem" he was interested. The ulcers cause pain when food enters their bellies, so they eat and stop...eat and stop. When my gelding's ulcers were fixed, he eats ravenously - all of his food in one "sitting". She looks ulcery to me - her coat and her general appearance - I only say that as she so reminds me of my gelding a long time ago.
BTW I started my guy on Smartgut by Smartpak, and Senior Grass Smartvite. He had been leaving food in his pan and once we got him on these supps. He improved drastically. He finishes all of his food quickly, his coat is nice and soft and has a nice sheen to it.
Glad she is putting some weight on but I'd watch her and consider a good ulcer supplement. I swear by Smartgut and it has pre and probiotics in it too :)