im not sure if it is depression. i read up on depression and it says that it is a constant feeling of sadness. My feelings change depending on the situation. e.g. a sad person will feel sad all the time, if they win the lottery they will be happier but then revert back to sadness. a depressed person will feel said, even after winning the lottery, they will still feel sad; i.e. no change to their sadness occurs regardless of the situation.