My mom won’t let me get a diva cup

I have used tampons the for 5 years and I am tired of them. I go through them in an hour and a half. I think the diva cup is fit for me but my mom said no. I explained to her that it will work better for me but she keeps saying “what if it falls out or leaks?” I would much rather use one instead of tampon, as they can hold for up to 12 hours. This would be perfect for at school or when I go on mission trips and can’t use the restroom every hour. How do I convince her? She says it will be too hard to change at school (but I won’t have to change it at school)