I completely agree with Julie. It would not be contractions at 6 weeks!
All pregnancies are different, for my first I had no cramps, and I miscarried at 13 weeks. My second, I had LOTS of cramps. In fact, I thought for sure I was NOT pregnant because I thought my period was coming. But I was pregnant. And it is was just my uterus stretching and growing. I actually liked the feeling a lot because I felt like I could feel something happening. It was reassuring to me. For my third pregnancy I did not have any cramps and everything went fine, she is 8 months old now. So you see, all pregnancies are different. You can't compare yours with anyone else.
If you see spotting or they get so painful that it worries you then go see the doctor immediately. If you are not comfortable with what the nurse says then ask for the doctor. If they don't let you talk to your doctor then get a new one.
Also, I see you are from Miami Beach, I have an EXCELLENT pediatrician on 41st and Royal Palm. I love, love, love her! If you are interested, e-mail me direct and I'll give you her information.
Good luck!