Hey Sarah,
I'm a Neuroscience major, and I also had a tough time deciding what designation fit some of my classes. On the AMCAS help page, its says that Psych or Behav Sci classes are non-science while Neuroscience classes are BCPM. So if your school has a Neuroscience dept. and you took classes in it, then those count as Biology for BCPM. If you took classes in the Psych dept., they count as non-science.
When I called the AMCAS "specialists," they said that the content of the class (ie bio or neuro based psych classes) didn't matter when making designations. In other words, unless these classes were taken in the Neuroscience or Bio depts. (or have codes on your transcript showing they can be cross-listed in these depts.), they are non-science. I took psychopharmacology, and it was definitely a biology/neuro class, but it was in the psych dept., and I had to list it as non-science.
Hope this helps.