Emma, i'm 21 weeks with my first baby.... and i too wanted to know when people first "showed" a while back, i asked my mum, friends etc.
The problem is "showing" is interpreted Differently. Showing can be looking a bit ROUND to yourself, or showing can be when you are obviously pregnant to someone who doesn't know you walking down the street. As opposed to looking a bit tubby
I was a size 6/8 before getting pregnant....but i'm quite tall, i then had SERIOUS morning sickness, so i was only a little over 7 stone at about 3 months. I thought my bump was never going to come and i was never going to feel pregnant. At 21 weeks now i am just Round, its not a definate bum, if i go swimming i FORCE it out further so i don't look just a little podgy in the tummy area My low jeans still fit fine, and everything else still does up, but when i sit down i un do the top button as it begins to dig in.
your bump will arrive with time, i feel like i have a little little bump- but nobody else would ever guess i am pregnant.
Congratulations on your pregnancy- but stop worrying & enjoy xxx