i'm not a singer, cause everytime i scream, after one song my voice is gone,
thats not singing, just screaming, don't ask me to "hold a tone, i can't",
but i noticed that lots of singers sing or scream ALOT harder during live, only cause they can't really hear themselves,
the louder you hear yourself, the more you can controll your voice, and you'll tend to scream less loud, and fuck up your throat less fast,
sometimes monitors don't really work,
maybe its time to start messing with in-ear monitoring...
you can try that by bying some "in ear sony earphones", i got a pair of about €50 and they work fine, don't distort too fast, and since they are IN your ears they isolate prettu much noise from outside,
put a compressor on the signal for in ear monitoring, so you can safely turn up the gain, make sure there's no way you can kill your ears...they're important !
thats only my two cents... HEAR yourself well and it might go better....