If I always count 365.2422 days inbetween birthdays on a clock, will I ever

[Tsutomu]

become a day late? I always go inbetween these 365.2422 day intervals between birthday to birthday or the length of the tropical year period which some people say it's 365.24219 or 365.242199 days. I use the year that's 365 days 5 hours 48 minutes and 46.08 seconds long. If this is the exact length of the year, how am I day off after 5 millenniums? 5 millenniums after my birth, it's July 5, 6991 on the Gregorian Calendar due to the fact it takes 3-1/3 millenniums for it to be off a day and I'm talking 5 millenniums. The Earth slows down in rotation and if I always keep the time intervals between one big event and the next one that's the same, what is the reason behind me being a day off? I thought July 5, 6991 should be July 7, 6991 because the year is 365.2422 days but it's actually July 8, 6991. What's happening? I always count in hours 8,765.8128 or 8,765 hours 48 minutes and 46.08 seconds or in minutes 525,948.768 minutes or 525,948 minutes and 46.08 seconds or in seconds 31,556,926.08 seconds. I'm not concerned about the sidereal year, anomalous year or precession for now but what about this?