Symptoms ??

Melissa
So I have been TTC only for about 3 weeks and after the 2nd time of trying   I started to have these symptoms: 
​Nausea
​Constipation
​Tender breasts
​Headaches 
​And some of my favorite foods don't sound appealing to me. I did have a "period" but it lasted shorter than normal. I took a test and it came back BFN. Was it too early to take a test? Am I going crazy? Is it all in my head?