Pumping at work

I started a new job mid-May, since the first week I've felt uncomfortable with how I'm being treated in regards to me pumping (1 female co-worker). She times my sessions, makes comments about if it were in season I wouldn't be able to do it. She has also stated that I do not deserve OT cause I take two 20 min breaks to pump. Technically we do not get any small breaks and we get a 30 min paid lunch. I know they don't have to pay me for pump time but they have been (not my decision). She feels it is unfair because if she needs to leave early they would deduct time from pay (also not my decision). Searching for advice on how to approach this situation as they may want to talk about it tomorrow...