Yes, when you request a refund, it works like they try to price the segments you have already flown and figure out the difference. So it is normal that you wouldn't get a lot of money back.

You may be able to just cancel the reservation (to avoid the noshow fee) and keep the ticket intact, and when you need to fly, you could give them a call to get them change it onto your preferred date (change fee will apply, and subject to the ticket's conditions)