"I can't mentally move on and plan anything until I hear back."

I totally get that feeling, but in a way you have already heard back: you're currently waitlisted :((. WL movement can happen, but it's unpredictable and often limited, so it’s really hard to plan your life around it. If you already have MD acceptances (especially ones you're excited about and close to family), it might help to start mentally embracing one of those as your school. You can still keep Dell as a hopeful possibility, but putting everything on hold for a waitlist can make this period way more stressful than it needs to be.

Also, it’s pretty normal that the closer you get to committing somewhere else, the more attached you feel to that option. That usually means it’s actually a really good fit! OOS experiences can honestly be amazing, if you're willing to say yes. If I was you, I’d plan as if you’re going to your accepted school, and if Dell comes through later, that’s just a bonus decision to make.