Bronwym,
You sound like me, I too would be estatic for a consistant 4-5. I have days I am confined to bed and I am also pretty much limited to 20 minutes of driving time (One of my conditions is sciatica caused by piriformous syndrome and the leg pain usually is aggrivated by any long periods of sitting) On my last visit to the spine clinic I was basically given the option of a fusion or live with it, I have DDD, a buldging disc and radiculopathy to boot I really dont want to add failed back syndrome in the mix so I am not having the fusion.
As for the original poster I dont have the answers as to how to deal with nosy people and what to say, it seems like the first question they ask is what kind of meds are you on but I would go with the poster who has decided that her meds are her own personal business and tell people that you do not discuss such things. I had a friend come to my house not to long after I was hurt and stole a bottle of meds from me, lucky for me she grabbed the wrong bottle it was vallium not my pain meds so the joke was on her.
I wish you the best and hope you can find someway to deal with this that is comfortable for you, just dont let anyone ever make you feel guilty for taking medications that allow you to live a normal life!