Should I be concerned?

I have a 2 year old daughter...had a normal pregnancy with her. Have never had a miscarriage or an abortion. I am 19.....dont drink or smoke and have never had an std. I am currently 7 weeks pregnant with my second child and am worried....when I was pregnant with my daughter I had morning sickness really bad ay this point. The only thing I have now is breast soreness. My first doctor appointment is next month. I heard if you dont have alot of pregnancy symptoms youll miscarry. Should I be concerned?