Hi Hana,
Actually, your producing pair is more of the exception. Amazons are notoriously hard to breed in captivity. While egg laying is common in smaller species like parakeets, lovebirds, cockatiels and some conures, most medium to larger parrot hens in captivity can go their entire lives without ever laying an egg. Even when they have a mate, some hens never lay eggs. It’s not necessarily anything wrong with the birds, but for whatever reason the conditions aren’t what they are looking for in order to breed. All you can do is be patient and hope the birds decide to breed.
Thanks for the update,
Brenda