Back to work and getting worried...

kagyq2

I just went back to work on Monday and am worried about the amount I'm pumping.  So far, if I feed right before I leave for work he eats at least two 3oz bottles and sometimes a third if I can't get home in time.  For the last three days I've only been able to get enough for two bottles at work by pumping twice in my 8 hour shift (evenly spaced three hours apart).  I haven't had any issues with my supply so far and usually DS can be satisfied from feeding on just one side when I feed at home, so shouldn't I be getting about two bottles per pumping session since I'm pumping both sides?  I pump for about 15 minutes in a quiet environment while looking at pictures/videos, and I use an Ameda Purely Yours.  Does 6 oz. in two pumping sessions at work seem normal?  Do I just need to give my body some time to adjust?  I'm just worried I'm going to end up having to supplement with formula once a day if I keep only getting just the two bottles at work.