I think you had better call your TA immediately, as the Zaandam is sailing the Panama Canal route in April/May and then it does the Australia/New Zealand South Pacific route in May.
Zuiderdam will be going to Italy the end of March for 3 weeks in dry dock and then she will start sailing in Europe. It looks like the May 8th cruise is from Venice to Barcelona.
We just got off the Zuiderdam's Xmas cruise, and had a good time. There is a lot of refurbishments required, like replacing all the chairs on the balconies and around the pools, but this will all be done when she is in drydock.
Someone has made a mistake in your papers, so I would check this out ASAP.