My DD has very shrinky 4a hair. When wet it's past her waist, but if we let it dry naturally it's not even to her shoulders. She's seven now, and I've tried all kinds of great styles on her that might work on your DD. Have you tried twists--single or double strand? I used to plait her hair and part it into geometric shapes. My DD's hair tangles like crazy if left natural, so we really don't do that more than once a year for a special treat. Braidouts are also great, just take down dry braided hair and put little clips or something--it gives a 'curly' look but without the shrinkage and tangling. My DD's friends went nuts when she wore her braidouts in 4 ponytails. She's possible the only black person in her whole year at school but she's very self confident about her appearance. She's very patient and loves to try new styles. "It's all Good Hair" is a helpful book with detailed diagrams on how to do stuff (great for me since I have totally different hair and had to learn from scratch--I'm also from the UK, but live in NY now
). She loves to look through the pics and choose a style--maybe your DD would enjoy that too.
The products you're using sound moisturizing. I don't think there's anything that eliminates shrinkage, though. I was looking at ancient Egyptian reliefs at a museum once, and I could swear one of them had weights hanging on the ends of her hair
Maybe one day we'll get bored and try that...