Personally I have a good relationship with my doctor and we compromise on situations. For example, before I've asked for an increase because my HydromorphContin wasn't lasting the time it should have been, she bumped me up and started a new physiotherapy program set up more for chronic pain patients, rather than the community physio I was already attending.
Usually if your drug doesn't last that long, it's a sign of tolerance not needing to dose more often. Like the above posters said, just make it known your concern about the acetaminophen and just be open and honest. I wouldn't hold anything back, if you were a drug seeker I'm sure they would figure out the sneekiness of how it works, as I'm sure they've dealt with those patients in the past.
As for the Benedryl etc. these things may keep your mind somewhat off of it, but they will not increase the analgesia, which you seem to need.
Be firm, but not aggressive; explain your situation and I'm sure you'll be on the right path to wellness.
Also, the role of the pharmacist can really help. They are more than ever involved in clinical drug therapy--they are the drug experts. Usually they don't require an appointment and they are of great help. Maybe get their input or opinion on things and take that to your doctor as well. Sometimes it shows initiative on your part to getting well, and also the advice of another health professional--specifically drug expert--never hurts to carry as back pocket information (sometimes literally written down) .
Good luck my friend. I hope you get the help you deserve! Also, good luck with your family in the future, but for now your health comes first, as you already know. Take care!