Ah, right, that star is on the spikes not on the exit space, I forgot.
Okay, so you've managed to get a spare cat, and the portal in the room giving you one spare cat would suggest you need one spare... but you're right you need one more. The entrance to the room is as wide as it is for a reason. There's a different solution to 11,17 when you start with an extra cat that will get you there.
If you need a hint, you won't take both original cats out, you need to sacrifice one of them fairly early to relocate a troublesome part of the level. Then you'll be able to take the other and both revived cats.