Just guessing, but with the width of a standard chair being about 30" (with arms) and considering that her breasts are lying on top of the arms, would it seem off to suggest that Jenny's breasts are about 9" in diameter? Again, no more than a estimate, but I would guess the length to be 20" long. Amazing enough, I just did the math and those dimensions equal her breast weight using a cylinder calculator.
The thing about projected growth vs size is volume (weight) has to increase 8X to double the size. So, doing a bit of math again, the cylinder (Jenny's boobs) would be like 10½" in diameter and 21½" long to be about 67lbs each holding to the same size ratio (not the big difference one may assume). I would estimate that to be mid to upper thigh maybe, considering I think she is of average height. With her breasts being so full and resistant to squishing, it is hard to imagine any bra in a proper band width supporting that projection, so I have to imagine a much larger band with a cup size that essentially only cups her ends (areola area) as being her only option; it would offer very little support, but would serve only to corral the girls when moving about. Of course, the problem with that is once again, without her boobs (hence weight) being on her chest, she cannot adjust her posture to balance the weight over her hips (ala Beshine) and it would just put pressure on her back muscles and spine trying to stand upright (and even worse if leaning forward to any degree). In the one video I saw where she briefly stood, she looked to be leaning forward, which would just increase the stress as the abdomen is offering no support.
This is why, from a physical standpoint, as we imagine extreme boob size, in order for it to be manageable or tolerable to the girl, it becomes increasingly important to have the weight in a position where posture can be adjust to center the upper body weight over the hips. Think of it this way; if you have ever hoisted a let's say 100lbs kid on your chest as you carried him off, you would naturally assume a swayback position to balance his and your upper body weight over your hips. You would never try to carry him at waist level, let alone below that. In this way, I can sympathize with Jenny; she appears to really love her huge breasts, but with the increasing weight, she could not adapt, secondary to where the weight is. Though people may not like the huge fake look Beshine presents, from a manageable standpoint, having huge round breasts on your chest is the sensible option. You have to admit, you never hear big implant girls complaining about back pain when they have good posture; slumping is always the cause. It is tough to have good posture with hanging breasts past a certain point because leaning back will not balance the load. So, if Jenny could have only seen her boobs increase in circumference and not in length, she may have thought less about surgery, and what a pretty picture she would be today; boobs weighing 95lbs each, and each being 12½" in diameter and 21½" in length. Or you could have the same weight/volume with boobs 17¼" in diameter and projecting 15¾", ala fake boobs.