I have several issues with fat grafting for enlargement of the breasts in a patient of your size. Firstly, the FDA has mandated that the use of stem cells harvested from fat are strictly to be done only under what's called in IDE which requires federal government application and approval. Secondly, it is presently not known how many fat cells need to be harvested such that the stem cells can be extracted and that these stem cells when added to a another amount of fat would render that fat more capable of surviving. I would imagine that a fair amount of fat needs to be harvested just to get enough stem cells to make it worthwhile. In a woman of your size, there's probably not enough fat to make a B cup breasts on each side let alone add stem cells. As far as which technique that you've mentioned provides the best stem cells or best surviving fat cells in the absence of stem cells, has not been tested. It is known that if you can control the pressure to less than 12 mmHg, you're more likely to have a higher amount of fat survival. I would make sure that the person you're seeing is really doing stem cells and not just adding either PRP or just plain fat grafts. Good luck.
Lipo technique for Fat Grafting
It is necessary to utilize the technique that does least harm to fat cells to maximize take. That means low pressure suction with traditional machine, or syringe hand technique. All other techniques you mentioned can increase fat cell damage. Be sure to consult with a board certified plastic surgeon
Using fat transfer to the breast
In my experience, unfortunately, for patients who have such low body weight as you, even with weight gain, it is not possible to obtain enough fat to be able to make a meaningful change in the shape and size of the breasts. Additionally, even though you will hear doctors talk about stem-cell in reached breast augmentation, the FDA has specifically determined that this is not a term that is allowed, and transfer our stem cells is considered completely experimental at this stage. Although this may change in the future, and it probably will change in the future because the technique is very promising, be careful about what your shoulder what your promised. Make sure your dealing with an honest and transparent board certified plastic surgeon.
If you are very thin, you may have no fat available for transfer. Planning to gain weight prior to surgery is not being realistic. Once you have surgery and loose weight, you will loose a fair amount of volume of fat transferred. Liposuction for fat transfer must be done with as little trauma to the fat cells as possible. Each surgeon has his/her preference for harvesting fat. Using PAL, tickle or any type of laser will damage cells and decrease survival of the fat. You might do better with breast implants. I would suggest meeting with a board certified plastic surgeon and discussing your options.
I have used nearly every device you are talking about. I find that the Vaser offers the most consistent fat for grafting with the highest percentage of "Take." Clinical studies support this notion.
Stem cell enriched fat injection I believe is really a misnomer in the sense that all fat injections have stem cells. Second fat injection to the breasts is not an exact science and often has to be repeated. I prefer to place implants for a more reliable volume result. Best of luck.