focusing on diet before exercise

I have a question.... and tell me if it makes sense or not, Im not trying to sound like Im a know it all! But this is a conclusion I have come to... So to lose weight you need to first find out how many calories you are consuming on a daily basis, lets say 2000. The next thing would be to find out how active you are, so we'll say sedentary. At my current height and weight (61"/ 195) my BMR is 1600. So at the end of the day I would have a surplus of 400 calories thus gaining weight. But if I cut that 2000 throught working watching what I eat and how much and consume 1200 calories a day keeping my BMR the same (sedentary burns 1600 for me) then I should come up with a deficit of 400 (instead of a surplus), therefore losing weight. I worded like this not to include exercise, not because I dont wanna workout, I just got off active duty army so I love working out and lifting HEAVY weights lol! But I struggled with my weight the entire time I was enlisted and worked out very religiously. It dawned on me that my problem with my weight might come from trying too much initially. I always try to diet and exercise at the same time! It never fails, I get even more hungrier from the extra activities and end up gaining. I get discouraged and quit because for me, its harder to control or restrict my appitite while working out. I've tried just working out first and letting my diet 'catch' up (meaning I'll focus on it later) and I lost ten lbs! But as soon as I missed a few workouts if felt like came back faster the second time around lol! This time I will opt to try getting my diet together first. The way I see it (and PLEASE correct me if I am wrong) is that no matter how much exercise or amazing feats I can perform in the gym, it will all go to waste by dinner time for me lol! So If I stick to a 1200 cal diet, no working out because it boosts my appitite, and get plenty of water and take a multi I will lose weight. Not as fast, which is not what I want I'd rather lose it slow... If I lose it slow it'll come back slow (hopefully!) Then once I get down to a healthier weight I will begin walking and calisthenics and build up from there... But that sounds to simple to me or like i might have misinterpreted the information I received. I am open to all suggestions and opinions! Thanks!