Congrats on baby #2. Wow you have some perseverance with the breastfeeding, good for you :)
I had a lot of issues with DD1 - bad/ no latch, so I pumped for the first 6 weeks, and took Blessed Thistle/ Fenugreek for low supply. Once the latching was sorted out (around 5 weeks), I let her nurse on demand, so my supply regulated itself and everything was fine from there. The York Region lactation consultatnt gave me a nipple shield to teach her how to latch, so I had no nipple pain at all.
With DD2, I had no problems with her latching on (she was born at home and she latched on straight away and suckled for the first hour after birth). However, I did have some serious nipple pain for the first three weeks - lansinoh is your friend! My milk supply is great and no problems (no herban supplements this time around)
So, different experiences for sure but it all worked out. That being said - I think you can never be over-prepared. Breastfeeding is a two-way relationship, and whilst you may have some experience, baby has to learn, too. Good luck!