What are the odds that I'm pregnant?

not very likely, since your still considered underweight, your body won't be willing to get pregnant until you have enough fat to help support a pregnancy. If you do get pregnant then you run the risk of having a miscarriage. You need to seek help for your eating disorder, you should gain enough weight so your BMI is at least at 19. You also have to understand that you will gain weight during a pregnancy and you'll have to be prepared to handle that, mentally.