Most of my ECs are science (particularly bio) related (e.g. bio olympiad, microbiology research, etc.) but my bio teacher doesn’t know me very well, and I would much rather ask my calc teacher. Would that seem strange to adcoms, if I have very few math-related ECs and awards?
No that would not be strange. Ask the teacher you feel can give you the best recommendation - -one who can best speak to your academic and personal strenghts.