I agree your list already seems to have plenty of balance and if anything it could probably be cut a bit. I also note that if you apply to a rolling college like Pitt early enough, you could get an early admission and then use that to cut out all the other applications you don’t need at that point. Of course this assumes the rolling college is not rock bottom on your list.
Which leads me to my first suggestion for an additional school to consider, even though you don’t really need them generally, which is Minnesota. Minnesota is an excellent research university in general, and I think it is fair to say Applied Math is actually one of their strongest areas, although not the only one by any means. Technically the Math BS is competitive admissions, but to my knowledge it has not excluded any students for space reasons for at least a long time. They have some cool tracks they call subplans, one of which is the Mathematics of Data Science:
Not sure if that is where your interests will lead you, but this really leans into Minnesota’s strengths in IT stuff as well.
The Twin Cities are also great–fun, friendly, diverse, globally connected, and so on.
Finally, Minnesota also has rolling admissions, which is great for your purposes for the reason above.
The other school I always tend to mention to Applied Math kids is Stony Brook, which truly has a legendary Applied Math program, and I believe in fact they have more Applied Math undergrads than basically anywhere else in the US (including Cal, which I believe is typically second).
They have both an Applied Math and Statistics major and a Data Science major, also make it relatively easy to double major, also have an accelerated BS-MS . . . just a really robust program:
Anyway, like I said you don’t really need more schools, but I think in some ways these two are both special for Applied Math.