Thank you for coming back, OP. That can be a difficult thing to do, if initial responses really haven't been what you want to hear. The more detailed the picture, the more likely it is that people will be able to offer consytuctibe input.
I would have to echo the previous post in saying that your younger daughter, and your partner, are indeed likely to be biased in their opinion, but presumably that is why you decided to talk here? - to get a wider viewpoint?
Your DD does sound as though she has some deep seated anger. It could be PMT, or equally it could be related to childhood issues. In either case, she may well not be able to identify why she reacts as she does, but there are obviously some triggers and that might be a good place to start exploring the underlying issues.
The points you make about travel etc, in which she seems very unsure about action - but does enjoy herself when she follows through - could be indicative of someone with very low confidence. 20 years ago, I might well have shown those same responses ..."I don't think I should go, I probably won't enjoy myself, there might be all sorts of issues......". They are allied to feeling very unsure of oneself. To be honest, she may be showing that she is a very strong girl at the core, because she is following through despite her concerns. The fact that her experiences are then positive will hopefully help her to feel more and more confident in her choices.
You don't actually say in your posts that you want to fix this situation? If you do, the my input is the same as it was before ....more or less.
I think you need to begin really talking, on neutral territory, and bracing yourself to hear things you may not want to hear ....because only when those difficult things are out in the open will you and your daughter begin to move forward.
You will need to do more listening than talking, to begin with, and not refute what you hear because it contradicts your perception.
You need to get the ball rolling by saying that you love her, that there are no issues which cannot be fixed if you are open and honest with each other ....that you recognise that she is in adult, and that you would like to mobe forward in the way she has suggested o.e. talking with one another as adult to adult.
Start by asking why she feels angry with you, and where she thinks the anger stems from.
I have one question which may be relevant ......are your DDs full sisters, or half sisters? No implied anything, in asking, other than that core issues could be rooted in the dynamic.