Hugs on the post-op blues. They just show up and hang around and then go away again. It's a combination of things, including the drugs, but also the weird sleep patterns, the unusual routines, the nagging pain and slight fear even if it's small. It's a lot. It's a big trauma for the body and it takes some real time to get through to the other side. I give myself permission to have a big cry if it feels like I need it. I've also been art journaling--something I've never done--and it feels good to scribble and glue pictures into a book. I dunno why it helps.
Like you, I can't take NSAIDS, only Tylenol, and I dropped off the oxys to Vicodin about a month in, which my body tolerates a lot better. FYI and all that. I'm at 8 weeks now, so cutting back now on those, too, but I find that toughing it out usually isn't the best idea.
Hang in there.