Advice to telling a school councillor I think I might be autistic without a formal diagnosis

I think I might be autistic (self-diagnosed), but I can't go to anyone because my family members don't think I could be neurodivergent. I was talking to my grandma about my suspicions, but my mom overheard and said "You're not neurodivergent, you're just a kid.", whatever that means. I have social anxiety on top of that and find it stressful to talk to adults/ kids I am not familiar with. I can't build up the confidence for myself that I need. Sometimes I go non-verbal when trying to talk to people and then later have a panic attack/ autistic meltdown. any advice will help, and thanks in advance.❤️🌈🖤 (also I have depression)