Congratulations on your pregnancy. I hope things go smoothly for you this time.
Sounds like you had a lot of things going on with your DD - breastfeeding, expressing, topping up is definitely extra work for you - and not the best support.
Changing hospitals may be a good start if they have better breastfeeding support on offer.
Many mothers write themselves a breastfeeding plan, so they can clearly communicate with their carers about their wishes and preferences in different circumstances. Re low blood sugar, for eg, top-ups of expressed milk may be an option rather than formula.
Have you attended a breastfeeding education class at all? You said the ABA were not helpful - and I'm sorry to hear that - but they do run very good classes in the Perth area. I've found that learning how breastfeeding works has been invaluable in supporting my breastfeeding. The classes also cover baby-led attachment (or laid-back/biological breastfeeding), which can be a really effective way of initiating breastfeeding, as well as managing problems with feeding.
Having an LC on speed dial might be really helpful. Have you debriefed your experiences at all? I can also be helpful to talk things through and think about different options that you could try, though hopefully things will be less complicated next time round. Do you have a family history of intolerances? If you find yourself on that road again, there is an LC/dietician in Perth who specialises in that area, also.
Good luck!