I know the pain! It's so hard when everyone else can lose so quickly and you're stuck with the choice to go slow or risk not eating enough. (My current maintenance calories are like ~1450, which sucks. But, there's a lesson here, as a short person you'll never be able to eat as much as others unless you move more.)

Go off TDEE, rather than BMR. (BMR is the basic amount you'd need in a coma, which you're not in!) The way I make 1000-1200 work is by fitting in extra walks and eating exercise calories from FitBit. I can lose 1lb/week pretty regularly this way. Any deficit will result in lost, even 100 calories/day. Focus on eating at least 1000 (it's okay not to hit 1200 every day, but don't make sub-1100 a daily thing if you can help it) and move a little more.

My weight loss has, quite literally, been up and down. (I know about ridiculous low calorie counts because I used to cut weight in high school for a sports team and I've had a few stints with drinking all my calories and not eating.)

• I lost ~20lbs cutting out drinking for a month and having my wisdom teeth removed right after the month. (150>130)
• I gained back 5lbs when I started eating solid food and drinking again. (130>135)
• I decided I was going to lose weight and lost 20lbs in summer term 2014, between May 1st and September 1st (135>115)
• I gained back most of the weight when I started my MA, ~20-25lbs (115>140 something?)
• I lost 15lbs over the summer (2-3 months) before starting my PhD (140 something>128)
• I gained about half of this weight back over the first year of my PhD (128>135)
• I'm losing weight at this summer from a "start weight" of ~135lbs. It's been about 2.5 months and I've lost about 15lbs. (135>120ish)

The most effective was the wisdom teeth removal, but I passed out on the way to a final exam because I wasn't eating (drinking) enough calories for a prolonged period of time. So, not recommended. FitBit calorie adjustments are a life saver though!!!

Feel free to message me if I can help with anything :)