Here's some information on implants and breastfeeding:
http://www.lalecheleague.org/cbi/bibimplant.html
Also, as far as waiting until after you have children, you'll get a different answer depending on who you ask. Personally, I was 27 and childless when I got mine and I've never regretted it. In my opinion, why not have the surgery and go through the recovery when you don't have to worry about who will care for your child while you're healing. In addition, you probably are more likely to have the money now versus after you have children. As far as what they'll look like after pregnancy, people say that most times they think they look more natural after pregnancy. There's several sites that has a wealth of information about implants. One of my favorites is:
www.implantinfo.com.
Pepper