You've had some fabulous advice so I will just add with a couple of tips that helped me feel less exposed when feeding in public. I would wear one singlet on top of the other so I could pull one up and one down. This was only the tiniest bit of breast was exposed, and that was covered by baby. The other thing I used was a maternity belly belt which covered my post baby belly, as I was more worried about that than breast.

Also, have a look for parenting rooms when you are out. There are lots, especially in shopping centres, that have nice feeding areas not in toilets. In other places if you ask they will often offer you a quiet place to feed so you feel less exposed. But remember, every time you are feeding in public and a young woman sees you, you have helped normalise it for her so that she feels less concerned about feeding her own children when they arrive. Small thing but it helped me if I was anxious about feeding in public.