I got my J&J booster at Neighborhood House. They’re open Saturdays and an appointment can be made here:
https://www.seattle.gov/mayor/covid-19/vaccinations
There’s also one in Southlake Union.
Stick with the J&J and get the one booster for now. Sure, we can “mix them”, but I rather not have to have a third appointment and can pretty much count on the aftercare.
I had covid last fall, now have long covid issues. The Because it started out as pink eye, an adenovirus, I wanted to use the JnJ because they used snippets of the adenovirus to build the structure of the vaccine. I knew the side effects would be a lot like covid for a few days, so felt more prepared for that first shot.
This time I had the quad flushot the week before my JnJ booster. I had horrible chills and a 102.1 fever for one night. That’s it!
So, just trust your gut and go with what you know right now.
Best of luck! Oh, and they took a lot of walkins the first weekend, too, so I am sure you’re gonna get right in either way :)