Propranolol will help panic attacks, it lowers your heart rate, so you may feel more relaxed, but i find with the type of anxiety we are experiencing it more prevents it lightly... (i am a blank minder, so it's not thoughts, i can just wake up with shakes etc which it defiantly helps with)
As for individual reactions, they are useful as a general what helps, but look generally. I've tried 14 medications which have all helped and some cured people and that's not even including Diazepam or Topiramate which I have both taken. I'm not discounting you Kyle by any stretch.
As for Diazepam - they aren't long term solutions or from what I can see even long term acting, once you stop, you are worse or if you are lucky the same, so not a solution, more a short term aid. They don't tackle my DP at all, they just help my anxiety if it's high. For reason i've just said, a pointless exercise, unless you are gonna get them for ever and rely on them, band aid IMO and not even one that gets to the route of the problem.
I have chronic headaches too Kyle, I've tried Topiramate, Naproxen, Tramadol and the usual rest (none of these are in the 14 medications, i don't count these). I don't know Kyle how you got DP but from what i've learnt, it's one of two things if these medications don't give any relief.. Sinuses or Tension. Mine are actually Sinuses, showed up on a CT and in an MRI a year later, so i've been living with it for a year. My Gp said the only option (or next) was a Sinus rinse, which I am currently waiting for. This is usually easy enough to diagnose, bend over for 30 seconds, if it is worse (and if it's all day) this will more intensive. If it was a substance (you don't have to say at all either way..) then that is very possible. Otherwise, it might be tension, anxiety cases this, unfortunately, both of these your neck and shoulders will be tight, so that doesn't rule on from the other, so my advice is figure out if it's sinus related first...
If i was to list what didn't and did help me, i would not help you as many of the medications i've tried cured others. The best thing so far was Mirtazapine + Olanzapine which goes very much with the usual AD + AS thing I was saying. This combo specifically might not help you, but what i've found is the type of combo is often as important...
(sorry essay..)