Test taken too early?

Kacy

my husband and I are trying for another baby. we had unprecedented sex multiple times a day, the week of my ovulation. I'm supposed to start my period tommorow. I had some dark brown spotting after sex this morning and figured it was probably implantation bleeding. I took a 5-day early pregnancy test and it came out negative...

Could the test have been too early or is it most likely that we're not pregnant?