What Causes Weight Gain,irregular Periods And Fatigue?

Hi... I am a 23 year old, mother of one. I had one miscarriage when I was 19. Periods have always been irregular, my guess is due to stress. I have always had weight fluctuation even since a child so it is nothing new for me. I do not have any facial hair as of yet, but have noticed hair thinning. I would like to add as well that I have had a swollen submandibular gland that swells and "deflates" to normal off and on for about 4 years now. I also have a lingual thyroid. My real health concerns started about 6 months ago when I abruptly stopped having a period, I have taken 2 pregnancy tests and have had sonograms, so NO not pregnant. I have had excessive weight gain in my mid section, but assumed it was from my career change from being a CNA back to the corporate, "sit on the computer" all day type of work. I now have swollen, itchy VERY tender breasts, nipples have been hard for about a month and now they are to the point where they feel like they are about to rip off due to pressure. I have acquired the "fat pads" buffalo hump and the "moon face", acne is not much of an issue, however my stretch marks are beginning to turn purple. I had blood work drawn EVERYTHING was normal except for my DHEA was extremely high and cholesteral was elevated. I am extremely fatigued and am now to the point of such aggravation. I was prescribed metforimen, but am anxious to try it, because I believe that I have cushing's syndrome and do not want to be labeled as having PCOS without being tested for other things. PLEASE HELP!!!