Welcome to baby Elsa!
I am so sorry you are having nursing difficulties.
I went through that with my first daughter and you are right, it felt like my world was falling apart. We did overcome it but it took a LOT of hard work. Our first 1-2 months were really hard. It was worth it in the end, though. We eventually had an exclusive breastfeeding relationship and she nursed for 2.5 years.
First of all, besides an LC (and make sure you're seeing an IBCLC) you should really talk to your local LLL. They were a big help to me. I was afraid to call at first and didn't really get hooked into a group until later, but they were so kind and supportive and so helpful. They will understand how much you want to nurse and should have some good ideas, things you may not have thought to try.
Second, if you are feeding her pumped milk and/or formula, I would strongly advise you to not use a bottle. I did at first and I think it made things worse--basically we were fighting nipple preference as well as whatever it was that was going on before. We switched to alternative feeding methods, cup-feeding or dropper, and that helped I think. The way I eventually got her on the breast was actually through a nipple shield. I didn't have a physical problem that required one, I think my daughter just liked it because it was similar to a bottle. After a few weeks of the shield I was able to get her on the breast without and we never looked back.
I hope you get lots of help and that your nursing relationship becomes much smoother very quickly!