I know with your first it takes can take a while to show, I've just got myself in a panic today.
I'm naturally thin and quite tall so it's not too surprising I've kept my figure. I've lost my appetite the past couple of weeks and lost weight too. A friend of mine showed me her sisters bump at 16 weeks (which is what I am now) and it was her first and it's really big compared to mine.
It is normal to be completely flat isn't it? Sometimes when I lie down, I can see a little bump but often it disappears so I assume it's baby moving round. I'm scared it isn't growing as much as it should due to my poor appetite although I've been trying to make up for it. I had a few cramps last night which I assume are growing pains so I'm hoping before long my mind will be put at ease.
I thought I'd stop worrying after 12 weeks, but nope..
still utterly anxious about things going wrong!