I just now realized where you are. The comment about the temperature is right. Give it another month as things warm up. It’ll fill in. When it starts getting weedy, just pull the large ones and wait until next year to apply a pre emergent over the area.
As for water, you need about an inch and a half a week. Ideally in two long sessions, not 7 little ones. Deep watering will help make the grass more resilient. If you are getting that much rain still, then you are fine. I know in my area we are actually below normal water. My irrigation will be on starting next week.