Demigenders are pretty simple, usually it's when you identify mainly with a specific gender, but another part or parts of you feel something else. I'm a demiboy, I identify mostly with being masculine, but another part of me is undefined or non-binary.

If you feel like demiboy suits you as a gender, then go for it!
It's all about what makes you comfortable and feels right to you. If you lean more towards androgyny or the no binary spectrum, there's also demienby or deminonbinary, if those interest you.