First things first, RL has priority over WoW. Always. At 16 and having to listen to your Dad, who is at no fault for wanting you to succeed, those are just things that you have to accept and move on from. Good luck on your exams btw.
Second, as a recruiter for a Heroic raid group, I would have benched from the raid permanently. Unless you actually came back, which most players never actually come back, and then you would have to earn your spot back just like any other recruit. Attendance is a huge issue for players that want to progress through heroics. Having to train pugs/lose gear to them, is a hindrance to your raid group and your progress. We are actually looking to replace some of our players simply because of their attendance. I wouldn't have warranted a guild kick but some GMs don't like having randoms in their guilds.