Late period!

For the last 3 months my cycles have been 28 days. Well this cycle I am currently on day 35, with no AF in sight! My hubby and I had sex right in my original fertile window. I have definitely been having some symptoms, but I'm afraid it's all in my head!! I took a pregnancy test on Friday morning and it came back negative. Wondering if I should test again tomorrow or if I should wait a bit longer? Thanks for reading!