Difficulties with wearing a device? discussion

Hi everyone, I’m dealing with another fitting problem that seems a bit unique. So far I’ve used the holy trainer (clone) and lately been wearing a bon4m small size. The main trouble is the cage slipping down, though for me it’s more about discomfort than security. When the cage drops, it tugs on my testicles which hurts. I tried going with a smaller ring size, but now I’m stuck: the ring itself causes some pain from being too tight, and the cage still slides down pulling on my balls at the same time. The fit is comfortable during daytime hours; problems usually pop up when aroused or while sleeping overnight. In terms of length, even when soft I fill out the cage well so I believe the length is appropriate. Any advice?