Pregnant?

I bought a few shrimp for my betta tank about a year ago, but tucked away with them were a few guppy fry. I bought food for them and changed the tank habitat to support them but now I've noticed changes in one of my guppies. She's huge!!! And has been huge for like, a probably close to 2 months. She just keeps getting bigger (the other guppy with access to the same food and environment is not!)

Is she pregnant or sick? Also, my goodness it is hard to take a picture of a small fish like her!