Also OP, keep in mind that more or less everyone gets questions around the where / what / how of their pregnancy and relationship. For some reason pregnancy (and early motherhood) somehow makes you fair game for a raft of personal comments and unsolicited advice eg:
When I told my mum I was pregnant, her first response was: 'oh. are you going to get married?'! (Been with dp 5 years)
And as others have said if you are married it's all qs about how quick / slow / planned it was.
One of my NCT group was in boots buying dummies for her 6 week old ds. He was none too happy at the time. The lady behind the counter suggested she open the packet and give one immediately!
My mil gave me several run downs on why slinging our pfb was a bad habit and we'd regret it.
Throughout pg random strangers will touch your bump/ tell you you are big/ small/ it's a boy / girl. Tell you about their birth, tell you how you should do yours etc.
The whole thing makes you public property somewhat.
I found it annoying too, what I'm trying to say is we're all in the same boat here no matter how your doing it. Part of parenthood is fielding others unwanted 'helpful' advice. There again, about 20% of it is helpful!
think part of it is a bit primal, part of it is that many people, esp in the older generation, take a while to get comfy with their daughters / friends daughters breaking the rules they had to live by. Part of it is people justifying or reassuring themselves of their own choices, part of it competitiveness. Etc etc. there aren't many people who are secure enough to respond to you for you without bringing their own stuff into it.
Good luck With everything! Xx