Also consider Azla Xelastec, these actually mould to your ears with your body heat and I think they might be the better choice for your specific situation. I also think they work better with the Dusk, they are short wide-bore tips and don't affect the sound so much. CP155 will boost bass more. CP155 are generally a good fit for that IEM though, I use them on the OG B2 where they also help the bass a bit.

But specifically for your case I suspect Xelastec might be the better choice. They size larger than most tips, you probably want to go down a size. I usually use L in SpinFit but mostly use M or ML in Azla and even have MS on one side on one IEM (Azla Crystal on the Moondrop A8). You'll probably want SS or S, maybe MS at most for your larger ear.

It's normal that stock tips don't work and you have to try a variety of aftermarket tips. It's also normal that one ear is smaller than the other, my left is slightly smaller than my right and while on most IEMs I do use the same size, some I get a better fit with a smaller tip on the left.

Xelastec and SpinFit CP155 on my Blessing 2s, you can see how the Xelastec have really changed shape a lot at this point, and also how much shorter they are compared with the CP155, which allows the IEM to sit further into your ear.