Small uterus??

I just came back from my Pap smear and the midwife told me my uterus is pretty small. Like too small to be measuring 8 weeks. She says it felt more like 6 weeks. I missed my period July 11 and tested positive two days later. I'm kind of worried! She said it could just be that I have a small uterus but it worries me that she said it feels more like 6 weeks. :/ has anyone else experienced this? Has anyone just had a small uterus but the baby was measuring correctly? I haven't had an ultrasound done yet which makes me even more worried!