I would simply suggest going to Best & Less or Kmart and getting some cheap ah bra type bras, in a larger size to normal. They're soft, and depending what you find more comfortable, you can take the padding out, or leave it in, or, do what I did..... took out the one from my "larger" breast (non cancer side), and left the other one in. Evened me up a bit. My breasts now have a 25-30% difference in size, so I do have a partial prosthesis. I've worn this since around 6 months after surgery.
Those bras are also great during radiotherapy, becouse of the softness of the fabric
Did you get your pathology results today?