I need help comming out

So I’m having trouble getting the motivation to come out to my family. I have already come out to some people in my school but anny time I try to come out I just go in to a overthinking loop and I just get overwhelmed and can’t do it and I know they will be fine with it as my uncle is gay but I just don’t know how to tell them and I think they might think it is a phase as I am still young and just going in to year 10 ( grade 9) and I don’t know what to do can anny one give me anny tips