Clothes shopping with a newborn

I'm a single mother and have no one to watch my son. I'm in need of a new wardrobe so badly as none of my clothes fit any more and I've got two outfits that fit.

I'm going to another state for 3 weeks to visit family and I would like to have stuff that fits and not only wear PJs 😂

Anyways my question is, how do you try on clothes in a changing room with a newborn?

How do you go clothes shopping for yourself with a newborn?

I could bring his stroller?