Ive been nursing exclusivley for almost nine months. I had some hand-me-down nursing bras and the be honest, I hated them! I found that a regular bra with a thin and flexable cup gave me enough support and was easily manipulated and folded under my breast. As far as tops go, I stocked up on a whole bunch of V-neck tees. I wear men's Hane's undershirts in a size too big (I would opt for a medium since you say you are small) around the house and to bed. When going out, the Hane's tend to stretch a bit at the neck so I found that something with a lycra/cotton blend held its shape and still allowed for the easy access needed. Victoria's Secret Pink line makes tees that I have become addicted to! If its cold out, I throw a sweater that opens in front on and I'm good to go. The tees are usually on sale for 2 for $25 and there are a TON of other options from Vicky's. Just think stretch :)
I also do what Dori suggested, cami's with built in shelf bras are a great option to wear under shirts that don't have the neckline your looking for. Lets be honest, we've given up so much for baby as is, holding on to a little bit of fashion sense is a small way to make you feel good! Invest in a few of these and you can continue wearing your pre-pregnancy clothes through nursing. I was feeling the financial constraints of having to completely reinvent my woredrobe, but with a bit of ingenuity you can make nursing easy and inexpensive! Good luck, hope this helped!!