I believe your asymmetry can be safely corrected with an outpatient 2nd stage procedure.
Without seeing photos, i would be curious as to whether you had radiation, whether your nipples were preserved, and how much asymmetry you had prior to surgery.
It is important to understand that breast reconstruction is a process. A mastectomy surgery takes away the size, shape, and symmetry of the breast. In order for your plastic surgeon to recreate these variables, it often takes 2-3 staged procedures.
I wish you a safe and healthy recovery.
Web reference: http://drpaulgill.com