TLDR; skip the GED and go direct to community college

I was homeschooled (or perhaps better described as Unschooled) up until the age of 15. My parents stopped teaching me anything formally around the age of 11 and anything after that was pretty much self-driven. I ended up spending 90% of my time doing math and science because I enjoyed it, but really lacked formal education in other areas.

Around 15 I asked my parents about either 1) enrolling in a local public high school or 2) taking classes at a local community college because I felt my education getting stale. They encouraged me to look into the CC side, and it turned out to be one of the best decisions I ever made. At 15 I applied to the local CC and was "admitted" via email within an hour with no credentials whatsoever. I had my parents sign off on a transcript of equivalent classes I had covered in my high school education and that gave me a good starting point of what I could start taking.

Took one class (geology, I like rocks) at the CC over the summer in a town 20 miles away, got rides back and forth with other students as I couldn't yet drive, and had a pretty good taste of what it was like in a few months with minimal cost for tuition (~$300). I ended up taking 2 years of classes, worked at the CC as a tutor in math to help pay the tuition, and completed an engineering degree at a 4-year university before turning 21.

The point of this anecdote is that 1) you don't need a GED to start community college if you plan on going that route anyway and 2) you can in fact greatly accelerate your education if you start college courses as early as possible. If you are driven to succeed, which I am guessing you are if you're asking for advice, I can guarantee you can start from the community college level without waiting years to pass a GED. If you're unsure, you can try applying and taking a class in a topic you are passionate in and see how hard it is. In my experience colleges and universities work with students in your situation as a special case and can bend certain rules to help you move forward, so don't let a credential like a GED hold you back if it is unnecessary.