To get an idea of distances and directions, I put together this map showing mostly known cities and towns, as well as a few I invented for the story.
Note the legend dashed line showing a person's daily walking trek over paths and highways. Remember, Sumerians hadn't invented the wheel yet. If anything, it might have lived as a potter's wheel, but they hadn't applied it to carts, so the overland trek from Nippur to Uruk, for example, would have consumed around three days.
The map of Nippur below is derived from the Akkadian clay rendering below it, ca. 1,800 BC. It's possible the Idsha-Uru was in a prior time the Euphrates river course.
Quite likely Nippur in Uruna's time 1,400 years earlier would have looked different. But the gate locations, temple position, and overall scale helped me as I wrote her story. I hope readers find it useful as well.