Oh (((((Sandra)))). I am sorry.
Since I did it all wrong I can only suggest what I found out so belatedly...
try not to pressure her.
Just develop a schedule of contact that YOU can live with (just your contact, since you have no control over hers).
What I did was decide that as her mother, I wasn't going to stop. So once a week, on Sundays (this was during a period of estrangement) I would call and leave her a voicemail. Very simple, light, no clinging or urging her to call, basically asking for nothing.
I kept it simple, e.g.: Hi, just wanted to check in, hope things are okay with you. I'm doing fine, busy week at work, and your grandma's puttering along. We have portulaca in bloom and I'm getting into ___ (some acitvity). Saw ___ last week, she's doing great. Well, that's about it, I need to catch some sleep. I love you, bye.
I just did it, week after week, never asking for any response. I don't know if it helped or not but it kept me calmer. And now, we're communicating again. I still like to leave most contacts up to her to initiate, except for a weekly hello message. And it's feelig better.
I hope you can hold steady, and know that she will change soooooooooooo much over the next few years. As painful as this is, don't write her off. She knows you love her and maybe being away from you will actually help her mature. My D needed to get away from me, we were enmeshed and I didn't know it. But now, I'm glad she's on her own two feet.
with love and much sympathy,
Hops