pumping at work

Does anyone else feel like an inconvenience while pumping at work?? I work with mostly men (only 3 other women in the office) and I feel embarrassed about needing the space and the privacy to pump. We have a lunch room, but it has these great big windows, so I can't use it. I have to borrow an office every time and I feel so embarrassed and like I'm an inconvenience. The other girls I work with tell me it's fine and not a big deal and the gentleman I use the office of is ok with it, if slightly embarrassed. I just feel bad that I have to kick him out every 3 hours...