Fitness Activity Level

I'm not sure what to do about logging my fitness level in my goals section.

There is only Sedentary, or Light Activity.
It say Sedentary is for if you're working in an office for example, and then Light Activity is if you're on your feet all day...

I do 50/50, as I'm in lectures for 3 days per week at University, and another 18 hours per week is spent at work, where I'm on my feet all the time. There doesn't seem to be an in-between.

At the moment it is set at Sedentary, but MFP doesn't know that I'lm on my feet for 18 hours of the week - what do I do about those?
Should I buy a pedometer / calorie counter and log those? Or do I not log it at all and leave it as 'extra'.

I don't want to put it as Light Activity, as I think that MFP will think I'm doing more than I actually am on a daily basis.