Small bump?

I had my midwife appointment at the 25th week and my bump is in fact hardly noticeable and measured 24.5cm. I haven't been sent for another scan and slightly worried however sometimes when I wake up in a morning he seems to move all the way up in to my belly and I have this bump from nowhere?! Thinking maybe possible he's laying low in my pelvis which is what she said in my first ever scan. Is anyone else the same??