Yeah, your model is not symmetrical but it is kinda close for things like the face.
i think this is possible: You could probably do a work flow where you use symmetry on parts that are symmetrical and then turn it off for parts that aren’t.
that may be tricky since I have never done it personally.
modeling something like this teaches a lot of good lesssons for future modeling projects though.
like next time:
Do I want symmetrical from the beginning and then pose it at the end?
Making a plan for you the modeling process will go down:
Blockout -> sculpt -> retopo -> rig or shape key
obviously get more detailed plan for each situation but at least you carve a path early on and expectations are set.
I think this post of yours will be great training for others coming for reference.
