I'm going to the doctor tomorrow but i'd like a quick opinion now about whats wrong with me please help?

Ok for about a year i have had extreme fatigue i'm 5'4 and i only way about 94 pounds. Im turning 16 in less than a month. I sleep from about 11 a.m. at night till 3 or sometimes 6 p.m. I eat normal and drink enough water and lately i've been having trouble thinking like during a conversation i loose thought of what i was going to say and forget. My father has Multiple Sclerosis has some of these symptoms and my grandmother has about 5 autoimmune disorders and has lupus. Please help i don't know whats wrong with me!!!