Adjustment of Status - I-485

How long is the medical exam valid for? I keep getting different answers. Filed in October received courtesy letter for medical December, letter said do not mail, I should take it to the interview. Completed medical end of January and overheard the receptionist telling someone it’s only valid for 60 days after the Dr. signature if in hand. I then call uscis to try to mail it since I thought it was valid for 2 years and I was just learning if this. Called uscis on two occasions and was told the medical is still valid for 2 years once I already submitted and application. It would only expire if I had it 60 days after the dr. Signature and didn’t file. Someone please clarify because I received an interview date for late April ( though most likely will be cancelled) and I wanna make sure I have a valid medical for the interview.