I was in a similar situation. Got no response from the employer (1,800+ employees - so by no means, small) when I came back after having my 1st child and nursing kinda tanked as a result. I went to HR when I was pregnant with my second and was told they just have to make a room available and they recommended I reserve a conference room or use an office of someone who was out for the day. So, not a super-accommodating plan.
To respond by saying "you have a right" to more/better space, is misleading. You may want such a thing, but technically, the law does not come out an say how much space or what the quality of that space should be. For example, employers are not required to provide a space that has a door that locks, or a room with an electrical outlet, or a room with a refridgerator, or a room with a sink, or even a room solely dedicated to pumping moms.
But really, you should absolutely ask or better yet, come to HR with solutions and numbers (i.e. the number of pumping moms soon to flood the workplace).
Ya know what ended up happening after my second? I had reserved a conf room, as usual, and posted an "In-Use" sign on the door. But a member of the HR DEPARTMENT! busted right in on me. Awful. I went so far as to lodge a complaint and THAT went no where. Nothing changed.