Hope you feel better from venting. Sounds like you really needed that.
to be a devils advocate, when you go into labor and if things move quickly, you may not have time to call every important person. Or you might be in pain and not even care about that. Perhaps you have a phone that you could text it to a distribution list -- or someone that will be with you. If you plan to do this though, tell your people that have text ability to look for it there too in case things go too fast.
When a woman is 9 months pregnant, it kind of is startling to see (needless to say). Many women in that month don't get out much so it isn't all that common to see a woman that big. Perhaps your clothes are kind of too clingy at this time too making it look like you are ready to "pop" the seams. Try wearing tops that aren't tight if you can find a tent big enough (ha).
Pregnancy has always been known to garner looks and foolish comments and actions (like strangers wanting to reach out spontaneously to touch your tummy). They like interacting with a pregnant person and think they are helping you celebrate your pregnancy and forthcoming child. You have been graced with a healthy pregnancy. Perhaps you can try to keep the mindset of a person being full of grace, love for silly, caring mankind, and of your blessing. If that doesn't work, tack a sign on that says "Crabby new mama here, just don't ask." (Okay, that was a bad joke)
I feel for you and those questions aimed your way. Perhaps you will teach a lot of people on here about what feelings might be going on inside a pregnant mom to where they watch what they say a bit better. Perhaps you could respond kindly with "Don't worry, you'll be the FIRST to know. I want you to come see us as soon as you can." From your generous response, they might relax a bit more. You could try to say, "Back off. &^&**, are you so dumb that you don't know I would call you? But that won't go over so well for your future babysitters. :-)