I’m 18 and pregnant but still in high school

I’m 18 years old and about to start my last year of high school, I am about 6 almost 7 weeks into it and I don’t know what to do. I’m constantly tired and having trouble with smells, I always feel nauseous, but I’m not sure how to go about telling my school, my due date is before I graduate meaning I have to leave to have the baby before school is over with. I am scared for my class to find out as I go to a very small school, I have told my boyfriend and my parents and they are supportive of me wanting to finish this year out but I feel like they only care that I am graduating. Another thing that I’m scared about is that me and my boyfriend have only been together for a short amount of time and I am scared he will leave if things get hard; I do suffer from bipolar disorder but a mild case making me a little mean to him as he says and I worry I’m going to scare him off. Also how do I tell my school I’m pregnant? Am I over thinking this whole thing?