You say she's 2 years old....so 18 months or 30 months old?I only have one hen and I eat/use the eggs as soon as they are layed! When my hen was on the laying mash from the co-op, her eggs had very thin shells and were very "watery," although they were fresh. While she was molting I changed her feed to a high end Purina Oyster Strong feed and now her eggs are slightly smaller but odd on the inside as described in previous posts.
Did she always have the thin shelled problem before this last molt?
3 weeks is pretty short cessation of lay during a molt...are you using supplemental lighting?
Is she drinking plenty of water?
Not sure a higher calcium diet is good during a molt,
she may have excess calcium in her system.
Too bad other birds are not present for comparison.
Just some thoughts.