This has got me thinking. Probably way off the Mark excuse the pun but is there a possibility that she's actually going to be adopting a baby girl but pretending she's actually carrying it.
Maybe she's had infertility issues and didn't want to disclose it publicly so she's going along with the charade of being pregnant but adopting instead.
It would explain the ever changing bump sizes if she's using different size bumps to maintain she's actually pregnant.
Like I said I'm probably way off, I like to look at all possibilities because you can expect anything from this swamp flump