Re: baby or fat?
I'm having my first.
I thought I was showing at 12 weeks, but in hindsight, it was definitely weight gain, bloating, and wishful thinking. I've been taking belly pictures every couple weeks also & going back to look at them definitely proves it's weight gain.
The actual baby belly didn't start until around 17 weeks...but then it was quite tiny, and only people who knew I was pregnant recognized it as a baby belly.
I'd say at Week 22 or 23 was when people at work who didn't know I was pregnant started wondering.