So for me I guess it’s because I don’t even find my husband sexually attractive. I have incredibly deep romantic feelings for him but not sexual attraction. As I understand it, demi is a sexual attraction after getting to know someone or being romantically involved (any demi followers help me out here) so that’s how I know I am one way and not the other.
That being said.
If you pick a label only to find it doesn’t suit you… It’s OK to change that label! We don’t always have to be even 90% sure because sexuality is a messy messy thing.