How do I convince my mom to let me wear tampons?

I'm turning fourteen in a little over a month and have been having my period since I was ten. I think I'm a pretty responsible person. I asked her about a month ago about tampons (I'm a figure skater and otherwise athletic too, so, um, you can kind of see how a tampon would be more useful) but she used the excuses that you have a higher chance of getting toxic shock syndrome than with pads (which I'm pretty sure is false, and I brought that up), and they're "hard to get in" (which, I mean, you can get over that eventually like learning to put on and take off contacts...right?). I also thought I heard her mumble something about "not approving of them anyways". I even said that I wouldn't necessarily wear them all day if she didn't want me to (and definitely not at night), just during sports. Still no. So how can I convince her? We're going to Target tomorrow and I told her I need a new contact case, because the contact cases are right next to the tampons and pads...how can I convince her, while we're there or however, that it'd be good if I could even do it just during skating and running and whatever other athletics? I can't use a pool excuse (I hate water and can't really swim). Help!