Meghan Trainor revealed she bought her son Riley a customized doll that looks like her to help with his separation anxiety. “My sweet 5-year-old boy is having separation anxiety,” the “All About That Bass” songstress shared via an Instagram video Thursday. “So he’s started using his stuffies, his Smurfette, and was like, ‘This is Mama, this is Mama,’ and I thought, ‘I’ll make a mama, I’ll make a stuffie that looks like Mama.'” “The thing is, I did,” Trainor, 32, admitted before showing off the mini doll with short blond hair and glasses similar to hers. “And he loves it. He kisses it, he hugs it,” she continued, as Riley ran over to her….