Chastity and orgasm denial discussion

Greetings. My girlfriend (who acts as my mistress) is seeking greater authority over me. She has chosen to purchase a chastity device, which I welcome because it excites me. However, we are unsure which cage would suit me best. My erect length measures about 17cm, though it shrinks to just 6cm when soft. I believe the CB6000s paired with a KSD-G3 lock is my ideal option, but I worry about pain during morning erections. Since I don’t have piercings and want discreet wear for places like public pools, does being only 17 make me too young for this? What do you think of cages that utilize a plug? perhaps something from here: or there: Can they be worn for at least a month? Thank you