6 weeks no symptoms..

Breann
Hi all!!
I am 6 weeks pregnant and we are very excited this will be our second baby!!! 
I went to the doctor today just to do the prenatal blood tests.. He asks how I was feeling and well I am totally fine.. I don't have any symptoms except I get some cramping,  super hungry and mild tenderness in my breasts.. I am going back for an ultra sound next week Dr. Wants to get a heartbeat on baby.. It's normal to not have any symptoms?? I am a little worried for next week.. Praying for that heartbeat!!