What to do when its a slow work day?

I WFH but we’re currently in a slow period, I have about 3 hours of work max a day. I use the rest of the time do chores but other than that I end up on my phone. I feel like with all this “free” time I should be doing more, but I also can’t leave the flat as I need to be available just in case something comes up. The other side of it is I’m 13 weeks pregnant and tired af. I feel guilty for using my time to rest (outside of chores) but on the other hand I feel so unproductive and like I’m not accomplishing anything