I think you only THINK it's small... she looks good to me, honestly. It's about the time in an autoflower's life when you want to start adding nutes but be careful! When you give her the first feed, use only 1/4-1/2 strength to see how well she's going to tolerate them. If she doesn't react negatively, you can gradually increase the strength but I've rarely seen any autoflower that can tolerate full strength.
Good luck!