8 days past missed period but negative pregnancy test?

My cycle is usually 30-31 days long. Right now my period is 8 days late. I was expecting it on Feb. 13. Took a digital pregnancy test on Feb. 16 and Feb. 20, both negative. 
Also took antibiotics earlier this month so not sure if that is playing a role. Very nervous I may be pregnant. 
Any thoughts?

Glow Resources

Let’s Glow

Glow is here for you on your path to pregnancy

Glow helps you navigate your fertility journey with smart tools, personalized insights, and guidance from medical experts who understand what matters most.

25+ million

Users

4.8 stars

200k+ app ratings

20+

Medical advisors