Trouble urinating after spay

I got my cat spayed she was peeing normally before she went in to get fixed spent overnight and when she came home she was barely peeing she is running around her appetite is normal she isn’t straining or meowing at all

Hello - What are the timescales involved here?   It is not unusual for cats to lose fluid when a spey operation is performed on them, especially if the abdominal cavity was opened in the traditional manner and / or they did not have a drip to make up for fluid losses during surgery.  This reduction in hydration is also impacted by the period of starvation and disruption before the surgery and may be enough to explain smaller wees.  However, witholding of urine can also be a sign of stress or pain and eventually become linked to cystitis.  It is important to speak to your vet about this; there should be a way to raise any post-surgery concerns that come up.

Did your vet leave an emergency number with you for phone triage?  (Triage is the act of discussing the symptoms in order to identify how urgent the case might be).