Hello Stix and welcome to the boards....
The first thing that struck me about your list of meds is that there seems to be little to combat what appears to be neuropathic pain. Opiates do not treat neuropathic pain well at all, which explains why you are not getting the pain relief that you feel is adequate.
A bulging disc is not the same as a herniationed one. A bulging disc is simply one that extends a bit beyond the traditional landmarks on the vertebra. It is seldom painful just because it is bulging. Have you had an MRI or CT scan lately to attempt to narrow down the exact causes of your pain levels? If not, that would be a great place to start. If the bulge is in an area where it contacts or displaces one of the exiting nerve roots , that might explain pain in your back, but not all bulging discs do that.....in fact most don't.
The traditional or tricyclic anti depressants do wonders for neuropathic pain, as well as lidocaine patches, Lyrica, gabapentin, and other anti convulsants, in the right doses do wonders for reducing pain caused by damaged nerves.
Have you had an emg? That is a test that is done to determine if there is nerve damage, and at times can help to determine the cause and location of the damage. If you haven't had one, it might be well worth discussing with your treating neurologist or pain management doctor.
Before any increases are added to your current medication regimine, it would be well worth your while to investigate what exactly is causing your pain and trying out some of these other medications, rather than increasing your opiates at this point..
I try to stick to the rule that less is more when it comes to opiates. Taking the right type of medications for the right medical conditions, is far more effective than adding more of the same , wrong type of medications that aren't what is recommended for the problem.