Ds is 3 1/2 and nurses 2 (rare) - 6 times a day usually, sometimes more on a day when he's ornery. Over the last 6 months or so I've been cutting down on NIP - say we are in town, instead of nursing him anywhere, I started asking ds to wait until we got to one of the 6 or so places in town where I'm comfortable NIPing (quiet places). Now I will only usually NIP in 2 locations in town. I give ds a choice of those places, and often he will prefer to wait until we get home (and usually if he requests this, we will just do what is essential and go straight home rather than dawdling).
In a mall, I will choose to use a parenting room to nurse now, rather than using whatever seat is available wherever I am.
It is mostly for my comfort - it is hard work to nurse a 15kg young child on your lap. And I get irked having to stay in one place for a while where it's busy and noisy and I just want to get out of there (those places make me feel stressed at the best of times). Plus, I dislike baring my nipples to the cold, so I don't nurse outside if I can help it - well, not in winter anyway!
I don't really feel qualified to give advice, but what worked for us was to set some small limits - like, we can't nurse here, but if you wait a few minutes, we can nurse in this other place, and gradually make changes that way. We have also been ready (and have done several times) to drop things and head straight home/to the nearest private spot when ds really needed nursing.
Good luck :-)