I think your mother should let you make you own decision about this when it’s your own body, especially since you’re almost 18 and legally an adult (at least in America).
when I started shaving, I was in fourth grade, so I definitely think you’re more than ready if you choose to be. maybe talk to your mom about how uncomfortable and self-aware you are and how it makes you feel. let her know you’re grown and old enough to decide for yourself, that you respect her opinion but also have your own.
please also remember that you aren’t ugly, invaluable, or lesser because you don’t shave, or haven’t yet. hair or no hair, you’re lovely and it doesn’t determine your worth. 💕