I can't help with the allergies, but I want to offer my experience with nursing my kids. I encouraged my daughter to wean at fifteen months (long story, health issues) and I was really looking forwarded to the opportunity to nurse my son however long. I was committed to nursing him until he quit!
I was so disappointed when he weaned earlier than I had hoped. He's always been very independent and LOVED food--when he had his first solid food at six months, he held the spoon, not me. His choice!
So, just after his first birthday, he went to one side only. I hoped it was just a strike or teething or something. About two months later, he didn't want to nurse at all. I couldn't find a single position or time of day that he wanted to nurse, even before nap/bed. He fell asleep great, just didn't want to nurse. He never asked for it in any way (and I'm a WAHM who pays a lot of attention to my kids).
I really felt like a failure because everyone says they'll go until three or more if you let them. But I was willing--he wasn't! Again, though, he is VERY independent in all ways and loves food.
So, I guess I'm saying to follow her lead. Be patient, maybe she'll go back. Give her chances, try new positions, but take her cues. And I wouldn't take the raspberry as "yucky"--it's just a cool mouth trick for them. I think you both will find a good path for you.