Starting to show already?

I'm 8 weeks & 2 days and my lower abdomen is really hard already. I know baby is absolutely tiny at this stage, but the uterus is about the size of an orange? This is my first pregnancy and I'm a bit over weight so I wasn't expecting this. My mother told me that this is normal, but a lot of people say your uterus doesn't come out of your pelvis until 12+ weeks. Just wondering if anyone else has experienced this? I'm having my first ultrasound next week so will have some answers then :)