I cry most days and just don’t know how to make things better
The change has to come in you, not her. This rejection is nothing towards what she'll be capable of in her thirties!
So, what do you do?
First, you stop crying.
Second, stop giving her 'everything', make a reasonable budget and a plan outlining reasonable behaviour (yours and hers) and stick to it. You don't have to share the plan with her, it's to help you put in place some reasonable boundaries.
Third, sort out your own life. Try new things. Revisit things you used to enjoy before you were her mum. Discover who you are now.
We don't help our dds by being too dependent on them. If you are strong, and can live without their closeness if you have to, she will have more respect for you. Gradually, she can learn that you are a person, an adult with your own life, not just 'Mum'.
You can't 'buy' love. Not with time, not with attention, not with money or goods. You just can't. All you can do is realise that you don't actually need it and that you have done your absolute best.
The experience she has/is having as your child is not exactly the same as the experience you hope she is having. She comes at it from a different starting point, has different life experience, different needs, and is just beginning to sense that she has some agency in her own life. Who does she have to kick back against - who is the person she trusts enough to be able to do that - well, that's you.
Ah, I'm old and wise. I've been on this path for twenty-five years or so. I have a magnificent, loving, generous dd - and one of the best things I can do to support her is to look after myself a bit and not make her the centre of my universe. Be your own King Arthur, OP. Save yourself. The rest will fall into place.