She certainly looks pregnant, but could not tell you how far along she is. Have a look in the live bearers forum lots of post and pictures in there to help you out.
I'm 14 years old, have been keeping fish since I was 7 (mostly livebearers) and basically, you learn from your mistakes Lost of research, and lots experience with pregnant livebearers
The gray female guppy is no closer than 3 weeks to her next drop. I am going to move this post to the livebearer section where you will receive better answers than in a general area like this one.
she looks pregnant but she could be showing her gravid spot and is actually just fat (i know from experience of that). keep an eye on her and see if she is getting stedily bigger. If she is, she is most likely to be pregnant.