Should we get our cat a friend?

My boyfriend and I adopted a 1 year old cat 3 months ago and she's still pretty shy. She let's us pet her and she will sit with us but only if we make her. She never plays with her toys with us but at night she'll play with them by herself. I feel like even though I try so hard she's bored. I was thinking of getting a baby kitten and seeing if that would help her come out of her she'll more. The adoption center I got her from only had her for a week until we got her, they told me not to have any other animals around her but I feel like they didn't do anything to introduce her to other cats. They mislead me a lot when it came to her. They said she was sweet and loved humans but she's always hiding and running away from us. If I was to introduce them slowly do you think it would be a good idea? I mean I love my kitty even though she's a brat lol I just want her to be happy and come out of her shell.