First of all- you have a battery drain problem, not a short problem--a short would either blow fuses or create heat and smoke.
I always do the amp draw test, not voltage test. Take all positive cables off battery, set up your DVM (turn knob to dc amps) for DC amps on the 10 amp connector- connect one end of DVM to battery positive, the other to the load cable. Keep doors closed, hood light off etc. Watch the amp draw go down as various components go back to sleep (BCM, light modules etc.) amp draw should read less than 50 milliamp (0.050 amp) like around .025 or so - this is after about 10 minutes and is the minimal draw of ECM etc.
If amp draw is greater than .050 amp after 10 minutes- then pull one fuse at a time (no replacement) until you see it drop-- if you replace fuses, expect components to have to go back to sleep again.
If all is fine, then do amp draw on starter positive lead, and alternator lead- alternator could have an internal short- seen it once- telltale sign is if it is warm after 6 hr sit.....