Yeah I think you definitely made some bad assumptions. You are 17 though don't worry. In a couple of years from now this wont bother you xD

You really should of had a solid way of contacting your manager, you might not even be to blame at all if your manager was supposed to use that app. The fact they had your number but you didn't have there's seems strange. But ignoring that email was... the wrong choice.

Your mum shouldn't have screamed at you.