Okay so here is my two cents as I have a similar issue.
I pumped in the restroom (in the stall) with DD and for the first couple of months with our DS. People were surprised, asked questions but I just kept on. Eventually they said they were impressed by my dedication. I just sat on the toilet read a book/magazine and pumped every three hours for twenty minutes.
Now that we have moved (we are in the Army) I pump in a restroom/locker room. I sit on the couch in the "locker room" area right in the open an pump; I do pull my shirt over the cones/pumps for a little privacy. One of the other women said, "I remember those days". Must people walk in look and quickly walk into the restroom area.
IMHO you are feeding your baby - its not an ideal situation but it could be worse. People will have to get over any issues they may have.
Sorry you have to worry about this!
But keep it up!!!:
BTW I have even pumped in the field (I am active duty) while training - I just brought an electric tea kettle with me to run hot water through the pump pieces. The milk I stored in the cooler with ice and once a day either I would run out and give it to DH and get fresh ice or he would come to me. It can be done!!!