Oh man, that’s a nightmare! Hope you were able to change before work.

I always keep at least one tampon on me, or in my car. Considering you are going to work, you are old enough to realize you should do that. even if you are a teenager working part time you've probs had it enough time to expect to keep stuff on you.

But she'd also have to stop to get to a restroom to put one in. Some people have heavy periods right at the start, so she probably couldn't even get there by the time she realized her period started. I for one use a pad for a few days before when I think mine is coming just so I'm prepared. Tampons are harder to do pre- flow.

Having pads/tampons in her purse or car doesn't help the fact that her pants are now imitating a crime scene. Irregular periods make it very difficult-to-impossible to even wear "just in case" pads.
OP, I've been right where you are. I was mid-period, had a sneezing fit at work, and had to go home and change because my pad had been overwhelmed (hello, clot the size of my fist!).
Female anatomy can be a real bitch some days.