I used a hypnotherapist for pregnancy stuff. She's in Richmond, if I remember rightly. Anyway, I don't know whether she did stuff for breastfeeding, but I know she'd had good experiences with breastfeeding, yourself.
I was reasonably happy with the experience, although it maybe wasn't tailored enough. She taped the session for me, so I could use the tape for relaxation later.
I think breastfeeding would be a good thing to do hypnotherapy for. In your position, I'd also have a good chat with your nearest breastfeeding counsellor (the BFN are good), both to figure out what went wrong, and to build a relationship so you'll be comfortable calling on her for help early, next time, if you have a hard time.
FYI, I had a hardish time with BF with DS1. We used shields, he didn't gain weight quickly, and he fed constantly. I did persevere, but it took a lot of work and stubbornness. I was ready for problems with DS2. But he had a better arrival, latched on well in recovery, and bf has always been quite easy with him.