First, I think it's a pretty normal (and understandable!) part of parenting that we occasionally throw our own wobblies.
Just a few thoughts - are you aware of any specific triggers? Have you talked about it when she's doing well? It might also be really worthwhile investigating diet, too. Even totally innocuous things like fruit can cause wobblies in some kids.
Hang in there. It sounds like you're doing a great job with difficult circumstances.