As long as you feel that your engineering classes had mostly bio, phys, math, or chem content and less industrial applications, I think you can call them BCPM. This question is asked year after year, and you'll find some people telling you not to call them BCPM and some telling you that it's to your best judgment. I called my biomechanics, continuum mechanics, and bioengineering physiology classes BCPM because that's what I considered them. AMCAS never corrected it and none of the interviewers had a problem with it.
If the AMCAS doesn't think that your classes don't count as BCPM, they will correct it and the record of the correction will remain on the application. If you decide to dispute it even after that, you'll need to send them some evidence that those classes are BCPM (such as the description of course content), from what people told me in the past. But this can lead to weeks of delay in AMCAS application processing, which is not good for schools that have rolling basis admissions. So it wouldn't hurt to classify your engineering classes as BCPM the first time (assuming those classes have BCPM content), but it definitely would if you decide to dispute it after their correction. Just don't classify classes like "finite element methods" as BCPM because that has mostly engineering applications content but rather something like "mechanics: statics, dynamics" which is considered physics.