My teens were a horrible, horrible time for stuff like this. My periods were ridiculously heavy, long and irregular. I hated to talk about it so always felt like I was the only person...
I have PCOS which basically means my hormones are a bit crazy and my main symptom was ridiculous periods. If you often have heavy periods, then speak to your doctors as there's a number of ways they could help (e.g. mefenamic acid, tranexamic acid - the latter was a god send for me, loved it!). Also, if their usually heavy you may well be anaemic.
These days I take the pill (not for contraceptive reasons, but to regulate my periods etc) and my experience now is world's apart! Occasionally I have a heavy day, but nothing like it used to be. Most of the time I'm okay just wearing pads, but when I was younger I wore tampons and pads and could still flood (it actually took breaking down in tears at the doctors to get her to understand). School was not fun!
From what you described, it doesn't sound like a bad leak, so I wouldn't worry too much.