Mine are spot on 149 days.
One manages to look like she's imminently about to produce triplets, from about 2 months before, and then finally pushes out one modest single. And still looks pregnant!
The other I wouldn't know was in kid, until about a week beforehand, but for I have them scanned,
As DW says - did you take them to the billy, so you know to the minute when the deed was done, or did they run with the billy for a while?