trash free & diva cups

So I told my mom that I wanted to start trying to slowly become trash free and she looked at me like I was an idiot and said "what about your period?" So I told her I could use a diva cup and that they are like $40 but they can last for several years. She didn't know what it was so I showed her a picture and explained it and she looked at me like I was dumb and said "I've never heard of that" then she walked away.🤔🤔 now what?