From what you have told me, having had a trans axillary approach to breast augmentation the outside portion of the breast pocket has stretched. If you would like to keep the same size implants, then some type of suturing that we call a capsuloraphy should be done. Sometimes, it is necessary to add something stronger than your tissues. In that case, I will usually use an ADM like Strattice. I consider this an insurance policy to avoid having to redo the closure should it pull apart again. Seek the counsel of a board-certified plastic surgeon in your area. Good luck.