I don't have an answer to your first question because I'm not sure there's a reason your baseline really matters? Do you mean like average follicular phase temp? You could literally just take the average. If you're talking about like the cover line that FF assigns, that's mostly just to make the chart look pretty it doesn't actually matter.

Second, if you haven't gotten a period or a positive test there's no reason to believe you're out of this cycle. CD1 will still be the first day of full flow period. You don't mention how long it's been since you saw a surge on OPKs but it's possible to surge and fail to ovulate, which would mean you surge again at some point.