Learn Turkish: Yeraltında tarım yapmalıymışız, ne var ki suyumuz bitmek üzere. - Apparently we were supposed to do agriculture underground, however our water is about to run out.

While ama just means "but", ne var ki is more formal and translates to "however," "unfortunately," or "the trouble is that...". It is used for contrastive reservation, meaning it introduces a significant obstacle or a frustrating catch to the first clause. Here, running out of water is the fatal flaw in the plan to farm underground.

Can you break down the suffixes in yapmalıymışız?

The verb stem is yap (do). It is followed by the necessity suffix -malı (must/should), the buffer -y-, the evidential past suffix -mış (apparently / reportedly), and the first-person plural ending -ız (we). Combining -malı and -mış creates the meaning of "apparently we are supposed to" (reporting an obligation from a third party) or "it turns out we should have" (realizing a missed obligation).

What does the structure -mek üzere do in bitmek üzere?

The structure [infinitive verb] + üzere means "about to" or "on the verge of" doing something. Since bitmek means to end or run out, bitmek üzere perfectly captures that the water is just on the verge of running dry.

Why is it suyumuz instead of following the normal possessive rules for "our"?