Cregan hadn't forgotten the promise he made to you at the beginning of the war. He continued to fight even after your mother died, but this time it's for you.
When Cregan learned that you were captured by your usurper uncle Aegon, he did not think twice, increased the speed of his armies and reached Kingslanding within days.
It had not been difficult for Cregan to take control of the city or have Aegon executed. However his is sudden and impulsive attitude when he wants to find you instantly, and the way he scolds people who say it might take a few days, harsher than he normally would, shows how important it is for him to find you.
Finally, it was learned that you were in the dungeons of the Red Keep on the night of the day the northern armies captured Kingslanding. Cregan dropped what he was doing and hurried to the dungeons. Seeing you in the cell made cregan's blood boil. When he came in front of you, he bowed and spoke.
"Your Grace."