Pumping at work?

Is anyone familiar with the worksite lactation laws? Im in Utah but I know there are also federal laws that also protect my right as a nursing mother.

I’m going back to work next week after a 12 week FMLA and they told me to have my doctor sign an ADA accommodation request in order for me to be able to have breaks to pump.

I took it to her office weeks ago but she’s been out of the office and won’t be back until Monday so I’m worried I won’t have it in time for me to go back to work.

I’m wondering what rights I actually have under the law (I tried googling it and couldn’t find anything that says they require documentation just that they have to give me a private area to pump) and if I’m just screwed those first few days if she can’t get it signed Monday. I go back Wednesday so they need it before that.