T shirt with a loose cardigan or kimono type top works well too - pull t shirt up, cardigan drapes at side and can be pulled across underneath to hide any tummy.
I find slightly looser tops are better as they allow for draping over exposed bits. Having a muslin to hand can also help for extra drapeage if needed.
I bought a mid-thigh tunic top for transitioning between maternity and regular clothes this time but it's actually really annoying as when I sit down I sit on it and then I have to shuffle around to pull it up and have too much fabric to deal with. Regular hip length t shirts are much easier.
I'm feeding a week old baby at the moment, and wearing my maternity t shirts and looser normal t shirts while my tummy deflates. I'll get a little more stylish as my body gets more back to normal and feeds are less frequent.
Don't get one of those covers. They look awkward as you have to peer into them or fumble around blind, the poor baby has to feed in the dark (even my week old newborn likes feeding eyes open to have a look around which he couldn't in a cover) and nothing is less discreet than a massive cover saying "look at what I'm trying to hide" :) It's much easier to just wear normal clothing, and then you can be as discreet as you wish just by being able to see what you're doing and adjust things (clothing or baby's latch and position) more easily, plus it's not making being discreet a big issue IYSWIM.
If you later find you prefer one, fine, but the early days of breastfeeding are much easier to accomplish without a cover getting in your way.
