Opinions??

Hey y’all!

So I’m on CD 37, i’m 19 DPO, and I’m 4 days late with AF. I took a test on the first day of my expected period and got a bfn. Is there a chance my levels weren’t high enough that it came out negative? I confirmed my ovulation to be October 30, by opk. My period has been normal my whole life since I’ve gotten it. Any suggestions??