My little secret!

I'm not sure why I haven't told many people at work that I'm pregnant, I just haven't.  My bosses know, my close teammates know, and that's it.  None of the kids have any idea and my other co-workers are just as clueless.  I know that it's only a matter of time until people start to catch on and I become the subject of work place gossip.  I work in a large school with 1500 students and over 80 members of staff.  I know most of them, teachers and students alike but short of sending out an email, which is an insane idea and would be flagged up immediately as improper use of school email, how am I expected to tell everyone? 

To me it's become a game now.  I like the idea that I have a secret that most others don't know.  I like guessing how long it will take people to get suspicious and start asking questions.  I'm 20 weeks today and so far I haven't noticed any whispering behind my back.  I'm fairly certain that I can keep it up for another 3 weeks, with careful wardrobe selection.  This would mean that I finished the term and would return after a 2 week vacation nearly 26 weeks pregnant and by then I should think that it will be fairly obvious. 

I know that my little experiment is silly and serves absolutely no point other than self amusement, but to me it's fun.  :)