Can you be polyamorous if you're asexual? Because I've been sort of fantasizing about living with 2-4 friends and we'd own a house that we couldn't afford independently ever since I was a kid. (I was even okay with them marrying and having kids with their spouses as long as we could afford it.) It sounds silly doesn't it. Some of my friends, well, I love them like family; I don't want to lose them to the tides of the sea or the gusts of the wind.
It does not sound silly at all! It is bizarre and frustrating, but very true, that our society assigns a lot more weight and privilege to romantic/sexual relationships than to other ones. There are active steps you can take to cement commitment in a romantic/sexual relationship that are not available outside of those relationships. So relationships, commitments, and even love that is not romantic/sexual can feel a lot more precarious. It takes an active 'breakup' to end a romantic/sexual relationship; friendships can 'drift apart' more passively. And this can feel maddeningly insecure!
If identifying as polyamorous feels right to you, and helps you establish the reality and future that you want, then it's a perfectly acceptable and helpful identity to claim. You may also want to look into relationship anarchy, which captures a wider breadth of thought around this idea that each relationship should be defined by its own terms and needs, not socially pre-determined levels of seriousness. There are some people I like to date and have sex with who I might not want to live with or raise kids with. There are some people I don't feel romantic/sexual attraction to, but love deeply and want to share a life with! Relationship anarchy makes room and language to validate and think about relationships in this new way. Another concept you may find helpful to look into is queerplatonic.
But in the end, whatever words you choose are secondary. "Chosen family" or "life partners" or "deep friendship" or whatever - having the right words is just a tool to allow you to do the real work of building these relationships. Be open with the people you want to create a life with. Talk about what commitment means to you, how you see your future together, your concerns about what might threaten the friendship, what you do and don't want from the relationship. Whether or not you identify as polyamorous is less important than whether or not you have the words to let you talk about who you are and what you want.