Spring admissions are also quite rare and not many programs offer it so you might also not get the choices you want. I believe subject exams are now offered in April, September and October, so if you apply in a year from now (for programs starting Fall 2016), you can get at least 2 more tries (maybe 3) at the PGRE.
In the meantime, I think it would be a good idea to find a plan to strengthen your profile in other ways as much as possible for applications in a year from now. For example, maybe you can set up a research position? Good luck!