Novices and newbies discussion

I’m hoping to give long-term chastity a go, but with my current cage, I get cold and purplish balls when an erection happens (though I know to take the device off then). This is using the largest ring that came with it; I think it’s 2 inches. My soft base measured between 1.9 and 2.1 inches across, which seems okay, but my erect base gets up to about 3 inches wide. Am I measuring incorrectly? Is chastity just not for me? What can I do? I’m only 19 with fairly tight testicles, so I really don’t have the budget for a custom-made device. Also, how cold is too cold in this context? People say that because your balls can’t draw up as high as usual, they stay cooler, but I wonder if that’s accurate.

I’d greatly appreciate any tips.