I agree with PP's - you're taking in too few cals for your body's needs and it's shutting down in response - the fact that your milk is drying up is evidence that your body is trying to expend less energy. Try upping it to 1800 cals or 2000 if you're exercising. A 1000 cal deficit per day should see you lose 1 kg per week, but it might take a week of eating more cals for your body to realise it can come out of starvation mode and start burning the excess again. Goodluck, I know how frustrating it is, especially when you're putting in all the hard work.