Asking mom about tampons

So my mom has only ever used pads for her period expect one time at the beach, and for the past 2 years so have I. I am feel as if I’m ready to use tampons, because one, I find pads uncomfortable and gross and two, I live a pretty active lifestyle and using tampons would just be more convenient. I have brought up the conversation twice and each time she has said no. I asked her why and she said “young ladies can’t use tampons. Tampons are for people who are sexually active.” I have told her many times that that is not the case, and that I will be responsible when using them. She recently bought a box of tampons, which I found odd because she again doesn’t use them and have just been sitting in her bathroom cabinet for two months now. I know that I could always just go steal one, but I don’t want to do that without her permission. Any advice?