What is my approximate bmr? every doc i ask says something dif. i get answers in a range of 1200-2000! i have no idea how much to eat. i retain a lot of water so i can't go by the scale. 5"1.5 20yo f, 109 lbs. not very active, sit in school all day.

Sounds OK!: Body mass index (BMI) is a better measure than basal metabolic rate (BMR). Your BMI is normal, i.e. you are height/weight proportionate. Probably no need to lose weight; current diet probably is pretty good in regard to calories (not necessarily in vitamins, fiber, other nutrients). Your weight IS a valid guide; variable water retention accounts for only 1-2 lb. Find ways to exercise more!