Is my molly pregnant? Pics included.
 

I know she has a tattoo and it's wrong, she was a gift. Is she pregnant?

She could be... It's kind of hard to tell. My guess is that she either is just a bit chubby, or she is barely pregnant.

At the base of her tail there would be a dark spot (gravid spot) that gets darker over time when there pregnant.

It's possible. It's hard to tell from your photos...but I have to ask, are you positive that's a Molly and not a platy? I'm sure you'd know...it just looks so platy-like. lol

Mollies can get kinda thick looking, especially females, and not be pregnant. But if you have boys in there, or if she's been around males in the last few months, chances are she probably is pregnant.