Aye I feel for you!
The last of the scanned ewes (a hogg) lambed yesterday, and she's hung on a good 10 days after the main batch were done (in three weeks). I now have at least two 'dry' ewes (i.e scanned empty) that have bagged up! So christ knows when they will come.
And I had a very similar experience with triplets, the only ewe that my scanner got wrong was a twin that was in fact a triplet and was the last of the 'twins' to lamb. . . . . right in the middle of a torrential, icy, down pour. . . . . . one lamb dead when I got there, one died 24 hours later, despite me getting it up, feeding, bleating etc, and one lamb left with the ewe!
Bloody sheep!