What Causes Lack Of Motivation And Mood Swings?

I am researching behavioral information on my daughter. Based on research but not an evaluation yet, trying to better understand her moods, impulsive remarks (sometimes no sensor), lack of motivation, concentration, follow through, and her blaming parents, mostly me, the mother, for everything she feels has gone wrong. She's in therapy, tried anti depressants (wont consistently stick with medication, and stops taking it. Makes her feel sluggish). She has a poor diet, sleep issues and very little exercise. No one has figured this out yet. Any suggestions will be appreciated. I know a diagnosis can't be made.