How do I convince her 😕

I’m 15 years old and I have wanted to try menstrual cups for so long, I talked to my mom about it and about the reasons I want to get it but then we didn’t talk about it for a while, I asked her about it again and she said no because they’re too messy and she doesn’t like the way they work (aka emptying the cup)

I told her that I’m gonna be using my bathroom so she shouldn’t really worry but she still said no

Now my mom is smh a clean freak she likes things clean (not necessarily organized so it’s not ocd) and she just isn’t convinced even when I tell her that if there is going to be a mess it’ll be in my own bathroom

I really don’t want to use pads again they’re just way too uncomfortable for me which is why I want to switch to menstrual cups and I’ve never used tampons but I’ll have to change them frequently which I also don’t want so I’m left with cups but I can’t convince my mom

Any advice please 🙏🏻🙏🏻

Edit***

I can’t just buy one because it’s not available where I live so I can only buy it online and I can’t do that on my own because I don’t have a credit card or paypal account or anything I can make an online purchase with, so even if I pay for it myself(which I offered to do) I’ll still have to pay my mom cash and she’ll pay with her credit card