To be honest with you, I believe that you're not eating enough.
Normal weight loss is 2lbs a WEEK.
0.5 lbs a DAY is obscene. Like, it's amazing, but not sustainable. I weigh under 180 lbs and I eat about 1800 calories a day- including breads, grains, and other delicious carbs. Everybody is different, but your body could be reacting negatively to not having enough calories. Why not up by 200-300 calories a day, and then when you stop losing on that, slowly decrease.
"do not give yourself the permission to self-medicate with food" - eat to live.
164 (Normal BMI).
"every day that you don't gain a lb back in a victory on it's own."