I suppose before I can answer that - could you post your thyroid numbers? Weight gain can be caused by a variety of things and if you say you are not on any meds - even for thyroid - I question a thyroid problem being your problem - unless your test proves otherwise.
How have you been balancing out your system? I am a very easy going person. I deal with stress quite well. I have never had any surgery and I am not on any medications. I don't smoke or drink. I just want to lose weight!! I just want to be in a normal healthy range. Yes, I have went down to just several hundred calories a day and still couldn't lose weight. People told me I needed to eat more calories. Now I am trying the low carb diet because I don't know what else to do.
How long have you been hypo and what is your lab test at? You have very fatigued and no matter how much you diet and exercise you are only burning your hormones out more and not achieving weight loss.
Healing has to start from the inside first before outside appearances can be done. If you have been "off" for a long time your body is in need of repair to get balanced first before your metabolism kick starts and starts to burn.
I know people on 700 calorie diets and still step on a scale after 4 to 6 weeks and have gained 5 pounds !! I was one of them a while ago.
Now I have been balancing out my system for a month now - and recently I lost 8 pounds with no real effort in exercising yet. I am still to weak inside to start a major exercise program. But that will come.
I work in a school too. I know the stress too well..... limit your stress. Do what you can and no more right now. Your body needs to get healthy inside.