If your testicles change colour, its not the right size ring. You should be able to get your index finger between the ring and your skin without too much effort. Also check if they retain normal body temperature. If they go cold, that is bad!!
Like @rockstar, I also wore my cage 24/7. With my original dominix cage, I did this for up to 4 days without taking it off at all (its fairly open and easy to clean, doesn’t suffer from sweat build up etc). The whole “not overnight” thing is manufacturers / retailers covering their backsides if someone has issues from wearing incorrectly sized ring too long.
I ended up looking on dhgate for other styles not available here and settled on a few short metal cages. For the length of the cage, shorter is better than longer, if your flaccid penis is pushed up against the end, thats about right.
As for what you can do to help change things up, serving as a sub
Prepare and cook meals, wash up afterwards.
Prepare her a bath with essential oils, candles etc, have glass of whatever drink ready
Massages
Spend time just cuddling her, showing she is the centre of your world.
Dom/Sub doesn’t have to be about sex, but when it comes to that, again, make it all for her with oral, toys etc until she is satisfied. Don’t hope or expect anything in return, its up to her to keep you caged or not, allow you to orgasm or not.
I used to love the high that came from giving her satisfaction without release myself. Don’t get me wrong, I love to orgasm as much as the next person, but its completely different knowing there will be no release for you during sex.