Each chicken is an individual, they can develop at different rates. Most of mine tend to get bigger the first month they lay at a reasonable rate, but after that it slows down. But they still get bigger as they age. After the first adult molt you can usually see another increase when they start laying again but they can still get a bit bigger. But I'd consider her eggs after her first adult molt her "normal" size.
The large one was a single yolk, and she laid another the same size the next day, so I guess she's laying giant eggs now...
I have not seen that big of a jump and it be consistent. Strange. Sounds like you are sure it is her laying all those eggs. I don't have an explanation for that. Chickens never cease to surprise me.