Yep that'll be ur uterus forming. It feels hard (don't prod it too much!)

Im quite slim (165cm and WAS 60kg) and didn't start showing til about 24 weeks, and even then it was only ppl who knew I was pg who could tell. Its only since about 30 weeks that strangers have noticed, and only in the last 1 or 2 weeks that ppl actually ask when im due instead of "really? Your pg?"....and im 37 weeks.

I know you can't wait to get a belly, I couldn't wait, but man your back will be sore and you'll be wishing in a few months that it was smaller!!!
GL