Hey… relax! 
You’re on TouringPlans.com! As long as you use and stick to your TouringPlan (that I assume you’ve already completed by now) you’ll be fine! I was last there over Memorial Day weekend - a very busy weekend, of course! And used touring plans (via the Lines app) and we never waited more than 15 minutes for any attraction. Yeah, it was crowded walking around, but the TPs are so great it doesn’t really matter! Make sure to download the Lines app. Use it so you can adjust your TP on the fly if/when needed. Make sure to bring a battery backup for your phone! If you don’t already have one, go to Amazon and look for “Anker portable charger”. Any of them will suit you fine.
And really, look at it this way… Wouldn’t you rather be in a crowded Disney World than in the real World? 