I looked fat for ages and then all of a sudden around 25 weeks it like exploded into a proper bump, then had another explosion at about 30 weeks. People started trying to touch it and then looked hurt when I kind of grimaced at them. One woman at work rubbed my bump and started talking to it before even saying good morning to me - I rubbed her tummy in return, said hi to it and then walked off. Think she was a bit surprised by my reaction!
It doesn't matter how big/small/fat/thin you look when your pregnant, each baby is designed for their mum alone so other people's opinions of what you should look like don't matter, as long as everything is healthy.