first, welcome to BL
that combo of opiates and xanax is a pure killer, literally due to synergy of combining two strong cns depressants. and also, opi wd sucks enough, and trust me you dont want to get hooked on benzos. when you combine you use less of each. as for answering where your tolerance is, no one can really tell you that. you know your own body the best. plus morphine as awesome as it is really a waste when you dont IV it. dont get me wrong it will get you high other ROAs (route of administration) most find to be plugging the most effective thing. cant help you there as ive never plugged anything.
do some searching and you will find lots of info on this exact combo. be safe and know your limits.
dont forget, you cant change the world when youre dead either.