Currently on 9 waitlists (yup you read that right) post-interview. Been updating schools but the wait has been really hard, and I'm not really sure what went wrong with my app.
Seriously, it's just too early to be thinking like that. It might have been your interviews, but you won't know until it's over. Statistically, you are highly likely to receive a few As (~3) by the time classes begin.
9+ IIs mean there was absolutely nothing wrong with your app, other than, maybe, the interview. As I said though, it's too early to make that call before WL movement really gets going. Resist the urge to fall into the SDN trap of thinking once you get to the interview that the A is yours to lose. It isn't.
Almost every school invites far more people than they have room for. Search for the
LizzyM staircase analogy for a detailed explanation of how things work post interview. A very short explanation is that your interview is just one of many inputs into a decision whether to give you an A. The fact that you received an II (or 9+) is great, but you still might not make the final cut for a number of reasons that have nothing to do with interview performance or something being wrong with your application, in a process in which 60%+ are unsuccessful.
That said, WL movement is real, every year. People get called, and, believe it or not, they are all on WLs, just like you.
Yes, some already have at least one A, but many don't. And very, very, very few have 9 shots. Being patient is hard when everyone else is posting about their As, but you've done all that you can, and it really is out of your hands at this point. At least for this cycle.
My advice is to try to chill for the next few weeks. Movement is going to come and, with 9 WLs, the odds of you receiving AT LEAST one call are extremely high. Good luck!!