Coming Out??😖😣

So I'm 13 and I've known for about a year now that I'm pan/ace. But I've just figured out that I am also nonbinary/trans which is just like wow so that explains how and why I feel like this all the time. I never really had a name to put for it and now it makes a lot more sense. But I don't know how to come out. Only 1 person knows and is totally supportive of me (my best friend). I'm absolutely terrified to come out to my mom who may or may not be homophobic/transphobic. I just don't know. And I love my mom but I just don't know how she'll react. Any advice??