There's an innate problem in that acting hurt, which I understand and think you are not offbase in feeling, is not what some busy young person wants to hear about and is something she might feeling like putting off dealing with, again and again. This is a young behavior, oft shared by elders too.
I'd probably start thinking about curtailing that financial support, but I don't think that's the answer either, as long as you are able to do it. I take it you don't live nearby? The best answer for this kind of stuff is actual talking in person (which you have tried to do, the talking anyway).
So, then what. I guess I'd be quiet for a while longer and see if she comes around.
I have a similar but different thing with my niece, the difference being that I'm clear she loves me and I know I love her. She's a luddite, almost fully anti computer, and only texts. She calls me once in a while, I miss the call, call her back, and poof, she doesn't get back. But I know her life and there's a lot of scattering in it. On my end, I live with low money and my cell phone arrangement doesn't include text (lowest possible service). Making calls on it is clumsy for me, but that's the phone I use when I call her... the problem there being that I don't know when is a good time, but I should call more often anyway. We're both the same on letting it go a bit. My regular comfortable phone has higher charges, which add up with a nice long conversation. So, time goes by. However, when I see her (it's been a year and a half now, she lives in California) or when we do finally talk, there is no difference, we are still go-to people to each other - which is its own quandary maker, as when we do connect, we want a long talk, thus the time finding.
I know an answer for me - I should write a nice long letter, print it, put it with a card, which she tends to save, and mail it, and then she'll call me when convenient.
Maybe that's an answer for you too, mags.