Hello, Welcome to JustAnswer, It will be a pleasure to try and help with your concerns.
Have you had Thyroid hormone tests done ?
I notice that you have not mentioned any Hormone level tests like Thyroid in your " already tried" section.
A Thyroid dysfunction, like a hyperthyroidism can cause you to loose weight and show other symptoms that you are having too.
I would advise you to discuss this possibility with your doctor and possibly have a complete Hormone level analysis done.
If these are normal, then the psychological issues like depression can be thought of, as possible causes.
I hope this helps you.