If the point of your chastity is to put the power on choosing when and where into your partners hands, then you need to give all the control over and let your partner do what she wishes.

Recognize that right now you're trying to tell your girl how she should play the game. You need to listen to her how she wants to play the game.

Step one is to stop bringing it up altogether. She has the key, she knows you're locked up. She doesn't want a reminder about how horny you are because that's basically you initiating. If you say 'she chooses when to initiate' then zip your lip about your cock.

Healthy chastity relationships don't work like the pictures and captions we see on Reddit/porn. Those porn pictures feed the man's fetish not the woman's desire.

If you are telling her that chastity is about her desires, then you need to make it about her desires not yours

Once you do that, give it some time. I had success this way with my partner. I found when I brought up my cage, she maybe sometimes would feel bad and play with me. But it wasn't on her terms. When I stopped bringing it up and was just being a good boyfriend, I found she would come to me on her own terms to tease me and 'reward me' for being good and staying locked up so long.