I am in the Pac. NW too. I always tell people 4 square feet in the coop too.
However, since you are all set up and all, I do have some things to say:
I keep all my chickens now in a shed. I have other coops but they are just shelters now. I have 30 chickens (some bantams and smaller breeds included!) in 60 square feet. There are no problems, since they just sleep, eat, and lay in there.
However-
I have a huuuuuuge run. It is a whole huge garden fenced in for them to run in. Also I have plenty of structures and tarps for them to hide under when they wish.
So, if I were you, if they seem crowded in the run, spend your money to expand the run a bit- maybe another roll of fencing. Your chickens are probably fine in the coop with that number.
If overcrowded, problems can be pecking and even killing each other, more spread of mites and lice (and disease).
I just know that when I look at my chickens (like I did this morning) before I let them out in the morning that they are fine. Everyone is calm, has a place to stand patiently, in the shed, on a roost or the floor waiting to get let out.
You see, I have made my shed overcrowded before. It was when I had all large fowl in there. I have 7 bantams now, and a couple of smaller breeds mixed into the flock. When it was overcrowded, in the morning the ammonia smell was bad when I first opened the doors. So if you smell that ammonia smell in the morning, it is dangerous for your chickens' respiratory systems and they might get sick. That would need to be remedied.
The very fact that the birds you added are bantams makes it that much better.
The only tricky time is when we get that awful deep cold weather, and it has been bad lately the past few years. I put a couple of hutches in the shed at that time with 100 watt bulbs for them to huddle inside (and they do).
You might consider setting up a huddle box area outside (I have used pallets and tarps to make huddle areas). I have noticed that mine tend to not want to go back into the coop during the day if they can help it, and they will stand in the rain unless there is a tarp available.
It makes a great difference to them if they can just get out of the wind.
Here are two of my huddle areas (we get a lot of wind across the chicken yard):