Symptomless Pregnancy?

I have a baby who just turned 5 months and learned last week that I am pregnant again. I am now 5 1/2 weeks along and have NO SYMPTOMS. I was sick as a dog my last two pregnancies (the first pregnancy ended in miscarriage at 8 wks). I am petrified that this is a bad sign. Has anyone had a similar experience? I am very happy about the pregnancy but scared to death of another miscarriage.