Good for you for wanting to be prepared and thinking ahead.
I'm wondering whether perhaps last time you actually had one case of mastitis that you never recovered from and the bacteria was never eradicated. Or your doctor didn't take a swab and prescribe a focused antibiotic. Anyway - focus on the future.
The second time round things will be different - the mouth/nipple/tongue combination varies everytime. Flat nipples can make things tricky but speaking from experience it's not always a problem - the key is good latching advice. There are some opinions that some of the methods used to help inverted nipples can be adapted to help flat nipples before birth e.g. wearing breast shells designed to bring nipples out or using a plunger type device and not everyone agrees with that.
http://www.breastfeeding-basics.com/html/flat_inverted.shtmlIn the case of oversupply there are techniques that can be used like block nursing or even cool compresses to minimise blood flow. This is something that can be fixed with expert advice assuming you have the same problem again - you may well not.
Definitely take up the offer of an LC. Good Luck.