The term "transfer" is something of a misnomer, as you don't actually transfer a H1B visa. It's a term that is used to describe your ability to start working for a new employer based upon your being in status as an H1B worker before your new petition is approved -- but each employer actually applies for a separate H1B visa.
Neither your time line nor your present status are clear. You should clarify your situation or discuss your situation with an immigration lawyer, as you have indicated that you need to make a decision quickly and we cannot be certain that anything we say will be accurate based upon the small amount of information you have shared about your case.
If the USCIS approved an H1B visa despite the petitioner's having asked to withdraw the petition, it is reasonable to infer that they didn't process the withdrawal. Why that may be the case, and what may happen in the future, I couldn't say.

