I am very sorry that you were not satisfied with your previous answer, I hope I can help you further until you are satisfied. Dr. Douglass is offline, so I'll try to help him out.
Dr. Douglass was correct when he told you that an oily substance usually is not a sign of cancer. However, in a woman your age, this still needs to be investigated, because any discharge is considered abnormal.
there are numerous possible causes of a discharge from one breast that is not bloody, and you can follow this link to read a list of the possibilities:
Fortunately, most of these possibilities are not cancer. However, it certainly does need to be checked out. I would say that since it happened after wearing a push up bra that it could be that you had a breast cyst that was compressed by the bra, and it then released its contents. These are usually benign, but may require drainage or removal.
I hope this was helpful. Please remember to ACCEPT the answer if you are satisfied, so I can get compensated for my work. Bonuses are appreciated if you feel I deserve it. If you have any more questions, Please feel free to ask me, Good Luck! Dr. SaulJE