How possible is it?

Holly • 22 years old from Alabama. I have been married to my wonderful husband since Sept. 2012. We have a daughter. Our family was completed when our Son was born in November 2015.
So I am 15w4d. I've had 3 sonograms so far. We've only seen one baby and only heard one heartbeat. I've lost 12 pounds. My husband's great grandmother swears up and down that I'm loosing weight because there is another twin hiding in there. I'm just curious of its possible to not know at almost 16 weeks