Help needed to understand all of this

Good morning!

I have been on and off of here since October of last year. I have a scale that will calculate my Fat, Water, Muscle and BMI along with my weight. Is it really possible to fluctuate several % in a day on the fat, water and muscle? I am trying to stick to 1200 calories in a day. That isn't so bad but my carbs seem to outweigh my protein intake no matter what I do.

I would like to lose about 15-20lbs and nothing I try to do is working. I am exercising 3-4 times a week mostly cardio but I am doing some weight training. I am 5'7" and 155#. Any thoughts or insight would be helpful.