This seems a very complex situation.
When she says she felt unloved, I believe her. She is showing many signs that she finds being around you difficult. I also think she doesn't have much consideration for you in practical matters because of the feeling unloved. She is so focused on her unmet emotional needs she doesn't have the space to focus on being considerate to you, and probably thinks she doesn't have to. She's been hurt tremendously by you, and is still confused by your relationship i think.
I think I would stop bailing her out and paying for things, but instead focus on the emotional side of the relationship. I think maybe she's not moving on to be an adult because she is not happy with her childhood and wants to get that 'fixed' before she moves on. Getting you to keep her in childhood in a financial way as a form of nurturing from you, maybe. I'm doing a lot of armchair analysis here but i have some experience as i was a little like your DD.
Apart from the financials, my mum could easily write a post similar to yours. I DO feel triggered by my mother, and i would see the offer of a trip as somewhat manipulative. I wouldn't trust her motives. It appears your daugher doesn't trust yours either.
But you can't go back and meet her emotional needs of childhood now. Have you ever been able to empathise with her and understand her pain about her childhood, without saying you tried your best? Have you been able to own the ways you fell short as a mother and a person? We all fall short, so it's not an indication of personal failure. Your shortcomings would have affected DD.
Apologising is not giving in to her. You can have strong boundaries around money and everything else, so you're in control of that. But really hearing, listening and understanding her childhood pain and the role you caused will make her feel seen and validated by you, and my gut feeling is that's what she wants.
My suggestion would be:
Deep level talk, understand the ways she didnt feel loved
Apologise, saying you never ever meant to make her feel that way. Tell her all the ways in which she is loved (NOT 'i did this for you, i did that for you), but talking about her and how much you love her
Set boundaries around finances, and a timeframe at which point you'll stop providing, whatever her reaction is. Tell her money isnt love and it's time for her to make her way in the world. You'll be her cheerleader, but you won't fix it for her!!
After that, let go. Once you've given her closure on the childhood, apology, and a reassurance she is deeply loved and valued, and set your boundaries re finance, it is up to her to respond. She will need space from you then, to grow into her adult self.