question! help!

I went to the doctor and I was only 1-2 weeks pregnant. They did ultra sounds and said that they couldn't see anything. I made the next appointment for Feb. 1st. That will put me at 6 weeks. They did blood work and said that it was right where it needed to be and that I'm early and that's why they didn't see anything. Is it normal not to see a baby or even a sac until about 6 weeks? How long did it take you guys to see your baby?