I wore the same thing almost every day, especially once the weather turned a bit cooler:
1. One of these Madwell v-necks two sizes above my regular size. They are very soft and comfortable and easy to wash. They were easy to lift up and looked fine over all my nursing bras. I bought 7 of them in different colors.
https://www.madewell.com/whisper-cotton-v-neck-tee-MB722.html
2. A pair of black high waisted leggings or joggers. I had (and have) a bunch, none were actual maternity brands. I like Old Navy's joggers, and leggings from Lulu and the Colorful Koala brand on Amazon. High waisted is key because it makes you feel more covered up when you are lifting your shirt all the time to nurse -- something that pulls up and over your belly, but is nice and soft since your baby will be right up next to it. I liked having a variety, some leggings some looser, depending on whether I was just at home or going out somewhere and wanting to feel/look a bit more pulled together.
3. A big draped cardigan. Can something roomy but not too bulky. I like this one but there's lots of options out there:
https://athleta.gap.com/browse/product.do?pid=980125062&cid=1005761&pcid=1005761&vid=1&nav=meganav%3ATOPS%3ACATEGORIES%3ASweatshirts+%26+Wraps&cpos=31&cexp=1501&kcid=CategoryIDs%3D1005761&cvar=11273&ctype=Listing&cpid=res21082117980586738316615#pdp-page-content
I breastfed in public all the time but am a modest person by nature and liked having some layers for privacy.