Unsure what size Spectrum binder to get

as the title says, i dont know what size spectrum binder to get. the sizing chart recommends a small for the regular binders and extra small for the binder lights (36" chest and 30" ribs), however this is so close to a medium/small and im worried the recommended sizes will be too small (recently grew out of my size small gc2b binders but the medium i also have is pre-owned and stretched so its too big (i know its different size criteria but i still worry)). anyway, i was thinking about getting one binder light and one short binder before summer hits in full.

here are my questions, numbered for convenience:

1. should i get the sizes the site recommends or should i size up just in case?
2. should i size up in one and get the recommended size for the other? if so, which should i size up?
3. if i do size up and it is too big, could i use a dryer to shrink it? and is that safe?

(i posted this to r/spectrumoutfitters earlier but havent gotten a response yet. hoping i get better results here lol)