All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad, sallallaahu ‘alayhi wa sallam, is His slave and Messenger.
It appears that you are afflicted with whispers (concerning purity). So, we advise you to repel these whispers and not take heed to them. Hence, if you doubt whether or not you had any urine discharges during your sleep, then in principle, you had no discharges unless you are certain that you had any.
Also, we would like to draw your attention to the fact that staying for too long in the toilet when relieving yourself is disliked. Once you finish relieving yourself, you should take the initiative to stand up because staying for too long without need opens the door for whispers.
Allaah Knows best.