AANNNTTTT! You are fine. You are in remission. You have no disease activity.
This made me smile, this is extremely familiar, more so in the case of my Sister, who is having a hard time convincing them she's suffering. (Or at least getting them to admit that they know.) My file says "severe psoriatic arthritis", yet I'm not much worse than her, who is being told she has it very mildly.
The nature of the stiffness changes, but it doesn't disappear. Morning stiffness is a rarity for me now, but that doesn't mean movement/activity is by any means normal for me. I empathize with you, for example, if I needed to run up the stairs, I could physically do it, but it would hurt.
I don't walk with a limp despite being in pain, because limping doesn't ease the pain, but I sometimes wonder if I should get a cain, just so people don't assume there's nothing wrong with me.
"How can you have missed work yesterday, you look fine? Arthritis? So you're a bit stiff? You're not limping? My 78 year old gran has arthritis and says pilates does it wonders! So what like, do you have acupuncture? How come you can walk?"