Should I only eat 1200 calories?

Hi, being 5'1" 1200 calories seems to be working great for me. My first week was incredible but since then I've been averaging about 2.5-3 lbs per week weight loss. There are lots of tools out there that can suggest how many calories to intake to lose weight (including MFP) but your doctor probably knows best and can give more of a medical/clinical opinion.

Proper fueling is necessary for healthy fat loss.

Healthy loss yes, but less calories ALWAYS equals more loss. Plateauing dieters put in a controlled environment at the calorie intake they thought they were at lose weight, never heard of this not being the case. Poor record keeping is usually the culprit, but I'll say this again: The metabolic slowdown will almost never keep up with a decrease in calories, the effect is simply not that pronounced in someone with even vaguely normal body chemistry.

My fat is simply from too much pizza and chocolate combined with not enough activity. I'm now eating at 1500 calories and weighing/recording absolutely everything, and most of my liquid intake is diet pepsi, According to MFP I'm running a deficit of around 2400 calories per day and additionally I'm on the treadmill 3-4 times a week and not eating those calories back. Half the posters on here don't know the Krebs cycle from a bicycle but would have you believe I'm not going to lose any weight because my metabolism will slow too much, I'll be craving sweets because of my aspartame intake, and probably grow a second head just from drinking Pepsi. The reality? I feel fine, I'm losing weight hand over fist, I'm not hungry, and I already have more energy than I've had in years. I consulted a dietician and she hasn't told me I need to eat more and I trust her more than I trust someone parroting things on a forum filled with misinformation.