disabling bluetooth every time is probably more trouble that it's worth to save battery
Wi-fi will use more battery than bluetooth, the new versions of bluetooth are pretty energy efficient
if your watch is dying that quickly, i recommend an unpair/repair, sometimes it gets a bit wonky and that can straighten it out. this can fix battery problems, as well as other random strangeness.
(you will be able to restore from backup, and get all of your settings back)
is it possible you're doing a sideways swipe from either the extreme left or right as part of your bluetooth disable, as that will change the watch face
do you have the butterfly in your "my faces." If you don't use it, just delete it. You can add it again later if you want.
or make sure the face you use all the time is all the way to the left.