Advice needed

Hello, I've always enjoyed the idea of chastity. I've been talking about it with my gf and turns out she really likes the idea of teasing me, so I searched through here and gathered wisdom from you all, I decided to order the knockoff holy trainer...was so excited to try it out.

So we went to try it out, using the biggest size ring that comes with it we cant get my balls through, we've tried oil, in the shower, heating the cage up so the ring is flexible and all other methods I've seen suggested and the closest we can get is one ball in after a lot of pushing and pain. We've tried several nights now and I'm pretty disappointed. Is it normal to have so much trouble getting the boys in place? Not trying to say I have huge balls or anything...ex and gf have both said they're big but im not like a horse or anything. Any advice or suggestions? Is it supposed to hurt so much trying to squeeze them in? If so, I salute you guys, you must have tougher nuts than me.