Glad to hear they are getting larger.
One thing to keep in mind is that different breeds lay different size eggs. My Golden 300's lay more of a medium sized duck egg (like an extra large to jumbo chicken egg) and my Buff duck lays a slightly smaller egg and my Black Swedish lays a jumbo duck egg. Depending on the duck you may never get some of the eggs to stop wiggling in the carton but over all they should be like extra large chicken eggs or larger going beyond a jumbo chicken egg in size. At least that is what my experience has been in egg size. I hear the Pekins eggs can be huge.