7 days late and dozens of BFN

So, I stopped doing OPKS for a month or 2 due to the fact that the whole TTC thing was driving me crazy. Was only doing BBTs. Last period was on 1/24 and I was supposed to have period on 2/21. On 2/18, bbt was 99.9 and I did an opk for the hell of it and ended up being positive. We BD'd that day and went for vacation where I didn't do any temping. Came back home sick with the flu for 2-3 days. Did dozens of hpt from missed period till today and all were BFNs. So if I had a +opk on the 18th, current bbt down to 97.5 with little EWCM, when should I test? What are my chances of being pregnant? Should I wait for another week to test? No pregnancy symptoms. Came off BC last August and periods have been 28-32 days. Talked to my OB and she told me to give it another week to test. Any advise is highly appreciated.