It sounds like anxiety plays a major role in your condition. That's not to say it couldn't have some physical component or cause like sleep deprivation, neurological problem, endocrine disorder, etc. Because your depersonalization seems to be triggered by or at least related to anxiety there are a plethora of easy to follow tips and advice that will improve your situation. You can just do some research on anxiety on Google. There's a lot of low quality content out there for anxiety but also some great sources as well. I'll give you one tip that helps me. It's called triangle breathing. Basically you breathe in for three seconds, hold for three seconds, breathe out for three seconds, then repeat the process. If you're anxious you may only be able to do this a few times or not at all but it still helps in small doses. If this isn't helpful to you, don't be disheartened, because there are many other wholesome ways to soothe anxiety.