I just wanted to offer my personal advice for women wanting to BF with flat or inverted nipples or one of each as was my situation!
When I was pregnant I found it hard to get a clear understanding of what baby and I would be in for when we started BF with my nipples. I wasn't happy with just "It'll work itself out", I had a feeling it wouldn't.
Luckily I purchased online a product called The Nipplette by Avent, and took this to hospital with me. DD was 2.9kgs on delivery and her small mouth combined with my nipples made BF very difficult. But through using the nipplette device for a few minutes before a BF my nipples stuck out enough that she could attach and begin sucking. As she continued to suck, the nipple came out more. So BF was great for the nipple issue, it was the attachment that was the tricky part. The Nipplette was well worth the $90 for 2, we got our monies worth from day one. The breast pump was also invaluable, when I had to rest my sore nipples.
It took 8 weeks to establish BF, with cracked nipples causing all the trouble. But after a drug free 5 hour labour I figured I could handle that pain, so I persevered. And with lots of Lanolin cream and using nipple shields between feeds to keep my nipples moist and out, BF eventually became a beautiful experience.
Now DD is 10 months old and we're starting to wean back to 3 BF a day! DD loves BF and my nipples aren't flat anymore. So best of luck if you're in a similar situation to what I was in. It's tough but if you get the right tools to help you, it is achievable to BF with flat / inverted nipples.