How old are your ducks? I have 2 big duck hens (1 Buff and 1 Pekin, along with several bantam ducks that are somewhat of seasonal layers). Whenever my Buff goes through her annual molt usually in the fall, she takes a break and doesn't resume laying until the days are longer, usually Spring. My Pekin on the other hand never seems to take a break and I really hate that for her. She's the slowest molter ever and she continues to lay even through that. Sometimes she'll lay soft shelled eggs when she's molting which is extremely worrisome, especially since I actually see her gobble up oyster shell on a daily basis. I'd love for her body to take a break, especially while she's going through her annual molt. Your ducks sound like they're completely normal and as long as they're acting happy and healthy, try not to worry. Since you made this post, there's always a chance you'll start finding eggs (at least that's how things work for me sometimes)

My chickens are starting to lay again, especially my bantam hens, so the ducks shouldn't be too far behind