Am I doing something wrong?

Hello,
I am trying to loose weight, and I am writing down all the calories I eat throughout a day.
I weight 90kg, and I am 165 cm tall, and I average between 1100-1200 calories per day. It is telling me that I have to consume 1200 calories a day, but then when i go to the gym it adds all of those calories. I can't make up for those calories on top of my daily intake, and some days it tells me that I am in starvation mode. Even if I consume 1200 calories. Is this really bad? Or is it ok as I am just working out. Hope that makes sense, and someone can help me.
Thank you.