If you asked me, I believe your main priority should be your alprazolam habit.
Your doses seem to be all over the place, you go from a couple of milligrams to 20-30-40mg (if not more) depending on the day. This is an extremely risky thing to do, even more so when don't have a decent script and/or a super reliable source, it's really going to make your life much harder than it needs to be if you don't do something about it (at least IMO).
Before even thinking about tapering you should try to stabilize on a somewhat consistent dose of alprazolam (whatever works for you at the moment). A good doctor should be able to help you with the whole process, most of them are aware of the dangers of being dependent on high doses of benzos.
If you're honest about your benzo use they should provide you with a script and assist you during the tapering process (tell them that you'd prefer to do it slowly to avoid complications).
I personally think it would be a very bad idea to try to get them to prescribe you opioids right now... Most doctors will think that you're just looking to score drugs and might even be unwilling to help you with your benzo habit.