I wonder whether you possibly could have ovulated on day 26 instead of on day 13? Although cm wise day 13 seems more likely cm wise. But temp wise, day 26 seems a possibility too.
I guess you will only know for sure when you see what the rest of the cycle looks like. Isn't it frustrating that it usually is easy to see what happened in hindsight, but so hard when in the middle of it?
Yes, a sensitive hpt usually would have given a positive by now, although some people don't test positie till later, so don't give up hopes yet.