Clair, I'm so sorry for your loss of Isabel. What a heartbreaking situation. I went back and read your story after the OP made me curious.
I've been thinking about this thread all night (while nursing my own DD kept me awake) and finally realized what has kept it on my mind. It's nothing that the OP said, it's the whole situation and our society's lack of support of new mothers. Where was everyone who should have been helping when this happened? New parents are so isolated and alone, and that's just wrong. And the people that most new parents are most likely to have contact with (I'm thinking mainstream medical professionals) are more likely than not to have little or no training in supporting breastfeeding. Can we use this as a wake-up call and GO VISIT those new moms? Bring them a hot meal, wash their laundry, admire their baby, take them a La Leche League meeting notice, listen to their questions and concerns. . . I know it's turned into a cliche, but it really does take a village.
Back to Clair's post. . .I don't know if having some frequent, in-person, experienced breastfeeding support would have made any difference for Isabel, but I do think in general it's critical for breastfeeding success when facing challenges. You've gotten some wonderful ideas from other posts, but I really want to encourage you to set up a support team NOW. Have you attended your local La Leche League group, or at least called a Leader if attending feels too hard for you right now? It's a lot easier to pick up the phone when you're postpartum and concerned when you know the voice on the other end. What about finding a local IBCLC? Arranging an initial meeting before your DS arrives, explaining your history, and coming up with a plan along with someone who will BE THERE to help might make a huge difference in your peace of mind.
Anything that interferes with early breastfeeding can have long-term impacts on how successful breastfeeding is. Using an at-breast supplementer, pumping and bottle feeding, etc. could all have negative effects. I agree with a previous reply, you have to make decisions that will make you and your family feel safe. However, if you do decide to breastfeed (and I hope you do, as personally I found/find it to be one of the most rewarding and important parts of my relationship with my babies), some experienced help will not only help with your peace of mind, it will help with eventually transitioning away from the tools and to exclusive breastfeeding.
Good luck and congratulations on your new little DS.