PG but confused about timings

[bellalaw]

Hi all
So after 2 pos digi tests last night (3+ reading), I'm pretty sure what's happening!
Confused though because 1st day of last period was 17th Nov... and I'm 99% sure I conceived on 7th Dec. But the "fertility" calendar doesn't list that date as fertile?
I tested on the 16th Dec and got a negative then.

Any ideas if it is possible that it was on the 7th Dec?
thanks in advance xx

Depends entirely on your cycle length and when you normally ovulate - most fertility calendars work off the theory of 28 day cycle, ovulation on day 14, but obviously this isn't the same for every woman.

Hmm OK - this wasn't planned so I've not been monitoring ovulation at all. I think cycle is above 30 days as the day of the month seems to fluctuate a lot.