Female led relationships discussion

I realize this might invite some teasing, but I am asking regardless. I live under chastity (CB 6000 s) and my release depends on when or if my Mistress wishes it. Being quite petite, I struggle to achieve an erection strong enough for her satisfaction. My Mistress has commanded me to find a “sleeve” that fits over my penis so she can enjoy satisfying intercourse. Yes, I know she is free to take a lover if she chooses this route; however, I hope to avoid that outcome. Is there a sleeve or sheath available that works over a soft penis and allows for sex? While anything goes, I would prefer one without belts.