First thing is up your calorie intake. 1500 is way to low. How long have you been eating 1500 cals for ?
At 270 you should be taking in atleast 3500 cals (That's 13xbw) and you should still lose weight.
Depending on how long you've been at such a low intake you might need to go above maintaince for awhile just to get things moving again ( thyroid ) . But start with the 3500 and see how things work. If you still keep the carbs out and take the fat/protein to a 60/40 you should still lose fat.
Just my opion