Nausea and vomiting

C
I have been nauseous for the past week and have vomited the last two days. I'm supposed to be in my fertile window now, but opk says not ovulating. The only time I can think of that I mighty have conceived would have been CD 9 or 15. On CD 22 now. Possible to be pregnant? Advice? I took a test yesterday and got bfn