Question: what are the signs and symptoms of three weeks pregnancy?
Answer: Implantation bleeding. If your little soon-to-be-embryo has already made it to their new home, you may see a bit of spotting as the fertilized egg burrows into the lining of your uterus.
Nausea. ... 
Breast changes. ... 
Missed period. ... 
Positive home pregnancy test. ... 
Positive blood pregnancy test.