Just had my first prenatal appointment

I am 6 weeks pregnant and just had my first prenatal appointment today. She checked my weight and blood pressure which was both good. She also checked my uterus size and said it feels about 6 weeks or so. I think it's kinda wierd that they didn't take any blood. They said they would do blood work next time which is in 4 weeks. She also gave me an ultrasound script. I have an ultrasound scheduled for this Monday, I will be 7 weeks along. While the dr was feeling my uterus  she said we also have to check for twins since I was on clomid.