Cut up carrots, celery and onion.

Turn on Instant Pot and select the saute’ setting.

Add olive oil and let the Instant Pot heat up with the lid off.

Add carrots, celery, and onion to Instant Pot and let it soften as it cooks.

Once it's softer (around 5 minutes or so), add in all other ingredients, press the soup function and put it on for 7 minutes, high pressure.
Make sure to leave at least 3 inches of space between the liquid and the top of the Instant Pot (otherwise you'll have a big old mess).
The valve should be set on sealing. Close the lid.
When the Instant Pot is done, use the quick release method to release the pressure (ie. turn the dial to let the steam out). Be careful, you could burn yourself!
Add Stelline or Pastina - if you don't have that, any small pasta will do. Close Instant Pot lid and put it on high pressure for 1 minute. Set on sealing and let it release naturally for 10- 15 minutes. Soup will still be hot, so be careful opening the lid!

Serve.
You may have to thin out the soup over the next few days by adding some more broth or water when you heat it up.