If you started at 175 and lost 50 pounds, you would now weight 125. That gives you a BMI (body mass index) of 23.6, which is in the NORMAL range for your height.
So, maybe you do not need to lose weight?
My guess is that 1200 calories is not enough
for you to be eating at your age and with your stressful job. It especially is not enough given all the exercise you do! You can probably eat more than that without gaining, but you'll have to track calories for awhile before you find out the number that's right for you.
Also, you need to make sure you are getting enough protein for all the exercise. If you feel tired a lot, it could be because you aren't eating enough, aren't eating enough protein, and are overexercising.
Take it easy--step back--track your calories, as jellydisney said.