It is not too late.
Your best course of action is to call Marriott Rewards. Talk to a rep and let them go into your account and then tell them the hotel and the nights of the stay. They will contact the hotel and they will confirm the stay and they will credit your account, accordingly.
Nice, simple, and easy.
I hope this helps.
Thanks everyone! Lisa an Internet Correspondence Specialist from Marriott Rewards Guest Services answered my questions.
Here is the link she forwarded on to me: Marriott Rewards Terms and Conditions and under EARNING POINTS #4 answered my question.
She further stated you can request credit for up to one year for any missing stays. So long you still have your receipt.
Thanks again everyone.
Happy and safe travels.