Hey there, as someone who's gone through this process twice, I dealt with that anxiety by conditioning myself to believe that I would receive news on April 15th. Sure, I could have heard something sooner but that's not a guarantee. What is, on the other hand, is April 15th. Once you condition yourself into believing that, it will help put the potential news out of focus and allow you to instead focus on what's more immediate, what's coming sooner. Since school has started back up now, concentrate your focus on your upcoming homework, that next test you want to ace, your next extracurricular activity project you want to create or may be working on, the next sport you want to compete in (if you play a winter or spring sport). Focus on your hobbies and stuff that you enjoy. Exercise as often as you can. Conditioning yourself for April 15th isn't going to make you stop thinking about an appointment entirely, that's impossible. But it will help you calm down and concentrate your energy on the next task at hand.
The waiting is the hardest part, but it's also the freest part since you don't need to do anything for your application anymore. This allows you to take your mind off of it and focus on living your best last semester of high school (or college). Good luck.