Foxy, I think you just nailed it on the differences between you and Beshine, perhaps without realizing it. It is, and it should be, about doing what makes you happy. You like the adoration of public appearances and dress to get that attention. Like you, Beshine cannot avoid notice, however, she does not seek attention and has dressed in a manner to avoid it. Two different desires, one open, one private, but with the same goal, the only one that really matters, happiness.
You never imagined yourself having breasts this size and still wanting more five years ago, so there was no way you would have been thinking as you do today, being almost overwhelmed and appreciative of all the attention. Who wouldn't love it, right? I think a dozen years ago, Beshine appreciated the head turning she caused in public, but at some point, you have to draw the line as to what you want in life; she decided she wanted more privacy. I can appreciate either choice because my bottom line is that I hope any girl with enormous boobs is happy in life and her choice, not just when in public, but even alone.
To that end, if you can maybe find that mysterious source, perhaps a polyurethane medical device manufacturer, that will make you the custom expanders of your dreams, that would be fantastic. It is not a contest, but achieving happiness, so go as huge as makes you happy. Just a note; though traditional implants are made of silicone, polyurethane is actually at least as flexible and more durable. Also, any implant can be made to be an "expander" with just the addition of a implanted external port a short distance away from the implant itself. And, as you are aware, seeking a size of a certain volume is safer than expanding a implant to its maximum, so think big and think safe, plan well and have something to support all that weight. Wouldn't it be great to wear a string neck halter at times?