Carrie has been sad a lot lately. She is down on herself, has very little appetite, can't sleep, and doesn't want to be around her friends or family. Carrie's condition is MOST likely

Depression

Explanation:

Depression is the overwhelming sensation of sadness that causes physical symptoms and it can interfere with normal life. Some of the symptoms of depression are loss of interest in activities that were pleasurable, appetite loss, difficulty to concentrate, insomnia, feelings of emptiness and guilt.

I hope you find this information useful and interesting! Good luck!