Is 1200 calories the right amount for me at 5'4 238lbs? i feel as if i am starving with the phentermine.

That is pretty low: You probably won't have a serious problem EXCEPT for major loss of muscle BUT, you use up about 2400 calories... net loss of 1000 calorie per day or a bout 2 pounds a week. Better is somewhat more liberal with weight trainginng to preserve muscle you might find this amusing...https://www.kickstarter.com/projects/1775472781/devils-diet

Eat: 1200 calories per day is likely to leave you hungry. An alternative to severe calorie restriction is to emphasize fresh fruits and vegetables, lean protein and complex carbs. Instead of counting calories, put your energy into living a healthy lifestyle with regular aerobic exercise, sufficient rest and nourishing food.