Hi. My guess is that you do have low thyroid. Here's why: every person I know with thyroid problems suffered for years while seeing the best medical professionals before someone actually properly diagnosed hypothyroidism.
For me, low blood sugar ruled my life for 4 or 5 years. I would eat 6 gigantic meals a day, towards the end, plus snacks, and still was a stick, with every jerk and jealous friend saying I was anorexic, notwithstanding the huge amount of food I was forced to eat and carry with me, instead of helping me through a terrifying time without accurate medical care.
It is very common for women in their 20 to have low thyroid. Esp. If they have grown up in stressful environs.
Other symptoms besides weight, or edema issues, low blood sugar symptoms, orange skin on bottom of feet or palms, hair loss, eye changes like gritty feeling or sunken or bulging eyes, large or slight bulge in middle of front of neck, hand tremor, night mares in morning when you wake up, muscle pain and joint pain. Facial hair, cognitive or memory problems.
This can be very serious as it only gets worse.
I think it is wise to see a doctor that is a natropath and an md. They seem to be able to diagnose problems like these that traditional doctors miss. Or else see an endocrinologist for thyroid and adrenal.
Good luck. Your post was so long ago, I hope things have finally been properly managed. I good news is once you receive competent care you will feel better so quickly! I started taking natural thyroid medicine and within a week much of the joint pain disappeared!
Btw: I have noticed that on every mystery diagnosis episode, that show on discovery health, at least one patient has thyroid or adrenal problems that go on for years while the doctor is saying tht the patient is making it up or something equally contempuous.