What should I set activity level to?

Blodyntatws99

Don't know whether I should set my activity level to sedentary or lightly active. Hope someone can help.

Basically, I work in a doctor's surgery, so although not physical or very active work, I'm constantly up and down all day. I don't do much exercise at the moment, and am managing only about 8k steps a day (back problems are limiting what I can do at the moment, but hoping to increase this over time and do a lot more). Have noticed quite a difference between my calorie deficit in mfp to that in the fitbit app, and wondered if that was anything to do with how the activity level is set. It's currently set to sedentary.