Normally, if the leaves stay curled no matter how well they are watered, this may hint to a root problem. This is not limited to overwatering. It might be, but it can also be a root infection of some type (Bacterial, fungal, viral). Another reason may be old potting soil crumbling into fine dust with little to no aeration. This plant should tolerate the three weeks of no irrigation.
If few days have elapsed from your last watering and the leaves do not uncurl and remain shriveled, it would be a wise step to inspect the roots. Take the plant out of its pot and remove the old potting soil. You may find some rotten rhizomes, and sometimes some intact rhizomes with little to no roots. If rhizome rot reaches a leaf, the leaf breaks off and falls. Cut dead and rotten parts. Let the cuttings callus for a week and replant them into a new potting soil. The damaged plant may take longer than normal to recover, but it may work.
Regarding the drainage holes: I understand you are using a pot without drainage holes because you don't want the water to drip inside the house (?)
It is better to use a cache-pot: Place a layer of pebbles inside a pot with no holes. Now place the potted plant inside it (with the pot). Let the water drain into the larger pot, but don't let eat reach the bottom of the container. Within few minutes after watering you can empty the excess water into the sink. I find that more practical than using a saucer inside the house. Nevertheless, saucers are a better option when plant is placed outside.