Jojo have got some much improved ones (I like their jumper and the yellow jersey one). I'm wearing a Isabella Oliver one right now (Asos sale, I'm not made of money), and that's pretty flattering - longline and dark grey.
Does Mamafeelsgood still exist? I have a black double layer top from there that I love.
Gap sometimes have reasonable things, but otherwise go for a vest top under your regular top/jumper. Or wear shirts?
All nursing clothing I’ve ever seen has been universally hideous. Utterly depressing. Maternity clothing too, if you can even find the bloody stuff. I just wore maternity jeans (the sole, wonderful exception) and my normal tops and all my normal tunics and dresses all the way through.
Oh another tip is wrap jersey dresses with a vest under - slash the vest on the top panel a few inches under the bra line - then you can feed in a wrap dress too (of course you can just use a wrap dress alone but I find a lot of them quite gapey.)
You know what I've taken to doing? Buying primark vests and cutting holes where my nipples are and wearing normal clothes aside from that. I wish I'd thought if it 11 months ago! Nursing bra don't - nipple though small hole , practically entirely covered up.