I tried clearing my sunroof drains and checked my hatch gasket and tail lights but I've finally narrowed down where the water is getting in. It's coming from the spot I have circled. Any idea what is causing it?

Edit: 2017 EX

 

As water generally flows downhill, I would start above the wet area.
Your best bet is to remove the interior panels so that you can better examine the inner panels of the car.
You didn't mention what year you had, but GD3 Fits certainly had an issue with cracks and leaks in the seam under the rubber/plastic strips that run front-to-back along the edges of the roof.
On the GE8 Fits, there are air vents located near your problem area (sort of below the tail lights), but I'm not sure if water could enter those locations under normal conditions (i.e., unless your car is sitting in 2 feet of water).

 

There's a body plug under that carpet. There is also a vent a little more up on the fender.

 

i had a leak in my '02 SI , was coming down from above the hatch . at any rate , you have to address this , as water accumulating in the spare tire well can do a lot of damage , it stays wet .i didn't catch mine for probably two years , by then it started a dry rot situation which eventually wasted the wheel well years later

 

I used silicone grease around all the grommets and plugs I could find. I also used some on the sunroof drain tubes. Hopefully that fixes the issue. I plan to keep this car forever or until I die, whichever comes first, so I'm trying to do proper fixes where possible. Putting a hole in the spare tire well would be a last resort.

 

Check your taillight gaskets. They are a known issues on all Honda's that leak in the trunk area.