i suggest
1300 cals per day... anything under that is really a bit iffy tbh and probs will slow metabolism down.
then
200
calories per day to burn weith exercise isnt that bad. 15 mins of situps in the morning and 15 mins in the evening would burn about 202 cals for me but my bmr is about 2250. you could try going for a walk/jog before breakfast. i sometimes do it and its supposed to boost metabolism amazingly for the day so then your metabolism is on like superturbo
just some ideas :]
good luck