I think they mostly crack them and slurp out some of the egg, than fly off with the rest to finish out in the field. We also have a fox that takes eggs too at times. Seems we are feeding the whole neighborhood.
Doesn't sound fully broody yet. When she is you will need a crowbar to get her off the nest. She also should be keeping a tight nest, and covering her eggs when she leaves. Perhaps something else is moving the eggs around like rats, or one year I had crows taking eggs.
Have you candled the eggs...