If your boss is OK with it there's no need to feel bad, your baby is priority plus if you don't pump you would get sick and that's not good for anyone. I also luckily have understanding coworkers, I used to pump twice a day at work for a couple months then lowered to once a day. At work it's could be a bit more tricky to wash and dry pumps, I only wash with soap and then put it in a clean bag. I only sterilise back at home.
I'm office bound, pump 3 times at work..we have dedicated nursing rooma so I'd just bring my laptop along but my teammates are aware that I'm pumping. I keep my pump parts in a ziplock bag or a wet bag and store in the fridge, only wash them once im home.