disconnect neg lead from battery and connect a multi meter between the terminal and the disconnected lead, set multimeter to read amps
you should see an amp reading above normal [anything above 1amp is wrong]
then remove each fuse one by one until you see the amps return to below 1 amp
this will pinpoint the circuit that is causing the drain
i did the same when i fitted a stereo and found i did not have a switched live
your problem sounds the same in that you have the memory live, connected to the switched and memory on the stereo
also check charging by putting a multimeter across teminals with engine idling you should get about 14v
check battery is holding a charge