I'm 25 and want to learn to play the guitar what kind of guitar is good for a petite woman?

Seagull makes really good guitars that will work great for a beginner. Martin guitars are really good too As females we have smaller frames and therefore there are a few things that we have to consider: will the guitar give you a good sound for a beginner?  and will it be comfortable enough for you to hold so that you can play? Also for better quality sound you should get a guitar that is made from real wood and not laminate.  That being said, the Seagull original S6 Acoustic guitar is a great choice for you.
The Seagull The Original S6 Acoustic Guitar  Features:

Solid cedar top
Wild cherry back and sides
Rosewood fingerboard and bridge
Tusq nut and compensated saddle
Semi-gloss lacquer finish  

This is one of the most highly recommended guitars for beginners because it is easy to use and comfortable to hold. If you rather get something cheaper then Yamaha FG700S Folk Acoustic Guitar is also a great choice. The Acoustic Guitar Features:

Solid Sitka spruce top
Nato back and sides
Rosewood fingerboard
Rosewood bridge
Black/white body binding
Tortoise pickguard
Diecast tuners
Natural finish

Don't forget that Martin guitars are good too. Martin sorts their guitars according to size, so you can also take a look at the site so that you can decide if you want to get another size guitar, you can take a look at the sizes that they have. Martin LXM Little Martin Acoustic Guitar is a good size for your small frame to handle. These guitars will last you, so the investment is worth it.