That sounds about right jims. But if your "at least 274" turns into 500 then you might be pushing your luck
The datasheet says 100K 'min', that implies at-the-very-least you should be able to write 100K times.
It doesn't mean numbers higher than that are guaranteed. Be aware of statistics.
As I said before, these figures are statistical (based on a number of tests on a number of samples).
So, Microchip are confident (in the statistical sense of 'confidence' and uncertainty) that you will be able to do it 100K times minimum.
This could mean 100,001 or 200,000 times, but as the number goes up the confidence comes down - that's stats.
If, however, you can spread your data writing to EEPROM over more than one 'cell' or cells (i.e. don't keep banging away on one particular cell) then you can increase the overall life. With a little planning your byte writing could be several x 100s of K. That's the rough idea behind a lot of Flash storage you buy .
There may be some test and analysis details on Microchip's website, I can't remember.
(I've struggled getting proper FIT test descriptions so good luck
)