Sorry to read what you are going through, as I can certainly relate. I am 5'3" and weigh about 94lbs on a good day, and am 45 and have two grown girls who weigh much more than me (that is just wrong!) and look so healthy, but I do not. I am asked constantly if I have an eating disorder.....or people gasp and say, "wow, you have had two children, are you kidding me?" Not what I want to hear at my age. I would love a good 10-15lbs on me. My arms are horrendous looking, toothpick like really.
Are you not seeing a doctor for your issues? Even just a GP to get you on the road to a specialist, perhaps a GI specialist? I am surprised you have come on this forum with all you are dealing with, including the lack of self esteem, which just breaks my heart for you. This is a wonderful forum, with wonderful, warm supportive people, but you really need to ALSO be seeking some professional advice.
Please take care....and seek some help from a GP or specialist, it can't hurt, and will probably help you immensely.