I'm only a smidge older than you- I'm 19, and I've been dealing with this for several years, so in that regard I kinda get where you're coming from. I've struggled too with what you describe... it's tough. I don't know if it would work for you, but I try to find something to repeat to myself when it happens, to try and keep grounded. Specifically, I find that reciting the date (or at least the year) seems to work, for me at least. Anything to remind myself that it's no longer X year, I'm no longer Y age, it's not Z date, like that, if that makes any sense. I'm not sure I phrased that well, I'm sorry. I wish you the best, and good luck.