I tend to use all of the above, except diameter counts, as that's kinda hard for a reader to visualize. Using spherical objects is easy enough, but it does tend to get a little stale. Sometimes I try to shake it up by describing it as 'being large enough to fit X inside', or how its wide enough to easily be seen from behind.
I tend to write more about hyprepreg though, so it's kinda necessary. You can say 'overdue with a dozen kids', but as nobody has actually done that, its harder to visualize and so I try to avoid that, too.
I tend to use relational comparisons. Whether or not she or someone else can reach around it. Whether or not she can reach objects, get in a car, etc. Something written into the story. Unless the character themselves says the month.
I can't imagine measurements or sports analogies well but I can at least hold my own arms out in front of me.