Is this a photoperiod or an autoflower? If it's a photo, you can certainly top or fim her but this is the earliest in the plant's life that you would do that. If it's an autoflower, don't even try as it's too stressful for the plant and she won't have time to recover.
She's awfully short for her age... try raising the lights to about 18" - it'll help. And I don't see any info on any nutes that you're giving her... I think she could use some good NPK to make her stronger.
Good luck with your grow!
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