I'm hopeful somebody more knowledgeable responds. I think the ideal way is to get the sound source directly to your hearing aids via streaming, but I don't think your aids support that and even if they did, it would require a device to wear around your neck. If you're going through an Apple Store, you could ask if they have any "better" earbuds that you could try. Also might want to look into apps that try to replicate hearing aids. They would let you adjust the frequency response closer to what you need. Again, ideal way is to stream sound directly to your hearing aids, but that won't be cheap, especially if you'd need new HAs. Sounds like you've already improved on your situation dramatically.
.25 .5 1 1.5 2 3.0 4.0 6.0 8.0
15 15 20 30 30 55 75 90 NR KS7
10 10 20 15 25 35 65 85 95 WRS 100/92@45/40