I'd flag the word "ultimately" in your sentence "But this does seem to give weight to the notion that even conscious deliberation is not ultimately free." The search for "ultimate freedom," like the search for "ultimate purpose," is doomed to fail, but only because the search itself is incoherent and hence ill-conceived. As you point out, ultimate freedom would require completing an infinite regress there's no reason to think we could complete. In that case, there's good reason to doubt that "ultimacy" is essential to the concept of freedom we ordinarily use and view as important especially in moral contexts. You summed it up nicely: "So you're free, but you don't have the impossibly infinite consciousnesses necessary to be ultimately free, right?" Right. Or at least the impossibility of ultimate freedom doesn't cast doubt on the possibility of freedom, just as the impossibility of an ultimate prime number doesn't cast doubt on the possibility of prime numbers.
Let me recommend (again) this book; the chapters in it authored by Robert Kane strongly emphasize the importance of ultimate responsibility (wrongly, in my opinion).