I don’t know much about the Agudah program, but my sister is now in her second year of the Bat Ami program and different schools I have taught in have had Bnot Sheirut from Bat Ami as well. From what I’ve gathered there are a wide range of girls in the program and you should be able to find a group that you’ll be comfortable with.
As far as your concern about rooming, my sister wasn’t happy with the first apartment she was assigned to last year and her advisor was very accommodating in finding her a situation she was more comfortable with. This year she met a family with whom she preferred to board and Bat Ami was fine with her doing that. So you don’t have to worry that apartment assignments are set in stone (as they may have been in your seminaries; I know mine was pretty rigid in that regard).
On a more personal note–Yasher koach! From firsthand experience, the decisions you’ve been making these past few years were not easy ones, and I’m impressed by your self-awareness, self-assurance, and maturity. You seem to be handling the culture shocks on both ends with a good deal more aplomb than I did when in high school and sem. Hatzlacha raba on whichever paths you choose, both next year and in the future.