With all due respect, only a 90LB bedridden person would burn so few calories daily. Therefore, unless that describes you, you need to improve the accuracy of your food intake records. So that's the good news; only the math is flawed, not your metabolism. Currently, its very clear that metabolisms between like-people (same weight, gender, etc.) don't significantly vary so metabolism is definitely not your problem.
Regardless of your food or exercise recording, first remember anytime you are attempting weight loss, come to a weight loss plateau or are gaining unwanted weight, you need to move more, eat less or a combination of the two if you want to proceed to the weight loss goal - PERIOD. The evidence-based (scientific) formula for weight loss is contained within the dotFIT program. Set your goal to lose 1-2LBS/week, follow the directions each time you enter a new weight and you will reach your goal.
If you follow the program, a measurable or visual reduction in body fat and/or weight should take place in a fairly consistent manner such as a decrease in circumference inches, and/or the desired average decrease in weight or body fat per week. If progress stops or slows dramatically, one or a mixture of the following adjustments will be necessary to re-start the process:
• Increase daily activities (e.g. daily steps or other non-athletic/exercise activities)
o Standing and pacing burns 2-3 times more calories than sitting for the same time period
o There are approximately 2000-2500 steps (depending on stride length) in a mile. Walking 2000 steps will burn ~75-150 more calories (depending on individual size) than sitting for the same time and only takes ~20-30min and can be done anywhere, even in the office, while on the phone or watching TV
• Increase workout time or intensity
• Decrease food intake approximately 200 to 300 calories per day or remove a small portion of your largest meal
Repeat the process any time weight or body fat is stable for at least one week. Always remember if you stop losing weight/fat, you need to eat less, move more, or a combination of the two regardless of what you read or hear from others.