Need Breastfeeding advice PLEASE?

I am pregnant with baby number 5.With my oldest son,I breastfed up until he was 3 weeks old,he had to have surgery and after discharged he nor I could ever get the hang of it again.Baby number two I breast fed until he was 6 weeks old then his doctor said I had to start supplementing with formula because he wasn't gaining weight(bull-crap)so I did and could never nurse again.Baby number three was born with breathing problems and was in the NICU for 2 weeks.I pumped for him had a little problem with supply but I believe it was lack on constant pumping&stress.Baby number 4 I breastfed but had very little supply my doctor offered me something to help with my supply but she had already gotten use to the bottle.Needless to say I'm dead set on having a successful breastfeeding experience this time.I will be having a c-section.So I'm looking for any tips/advice on how to up my chances of being able to breastfeed full time.thanks