Hey so tw depression/anxiety
I'm fairly certain I'm demisexual/demiromantic. However, I've had basically no experience with relationships or intimacy, despite being nearly 24, because of various life stuff, including mental health struggles with depression and anxiety. I feel insecure about this and I'm questioning if my acespec nature comes from that. Idk... I just kinda want to stop feeling so alone.
Demisexuality/romanticism (or any sexuality/romantic orientation, for that matter) does not require you to have experience to know.
Would you tell a teenager with no experience who is gay that they can't be gay because they have no experience? (I certainly hope you wouldn't, and if you would, you would be quite incorrect.)
With aspec identities especially, it can be very hard to characterise them with "experience," because they are charsctised by the absence of something. There will likely not be a moment of "oh, wow, that man that just walked by is hot and I definitely want to sleep with him" to tell you that you like men, or visa versa with women. Rather, it is often something that you will simply have to come about on your own, by looking for your lack of attraction and lack of experience.
Regarding mental health being the "reason" you feel demi, may I ask why it matters to you? Labels and identities are created to label our own experiences, our own feelings. If you feel that you are demi for any reason, mental health included, then congrats! You are a valid demi!
It is also alright if later your experiences change, and you no longer identify as such. People grow, change, develop, learn more about themselves, and it is perfectly alright and reasonable that your labels change with that. Labels are meant to help you grow, and to identify your experiences, and to provide you comfort. They are not meant to box you in.
Use whatever labels you feel comfortable with, anon, and don't be afraid to change them if they ever start to feel incorrect. It does not make you or your experiences any less valid. I also promise you that there are many people who can identify with this struggle, and that you are not alone.