are you sure shes overweight and doesn't just have a belly? If she truly is a pure pygmy they have big pot bellies. If she isnt nursing kids I would just have her on a mix of alfalfa and grass hay anyway, no need for any grain, though it may be helpful to hand feed her a handful once or twice a day to start taming her down. Keep working with her, you would be surprised how fast a goat will tame. I dont know that I would be trying to wrangle her down and clip hooves right off the bat(if shes not in dire need, you could tell from the top if they were) as that could be traumatic but getting her to come up and eat a hand full of grain or get her on a leash and just pet her assuring her you wont hurt her and then letting her go once she calms. Instead of dumping her I would think about getting a buddy, even a tame baby like your looking for. That will help to calm her as well as give you a baby to play with and she may eventually come out of her shell especially if she has a buddy that likes people to show her the way. But time and patience are key your not going to get anywhere overnight.