Need Help Wondering If I Should Continue Growing This Girl

I'm wondering if i should continue growing this girl she has two other sisters that are doing great but for some reason she isn't growing as well and idk what is completely wrong with her i looked up on what could be wrong and the only thing i could think of that she has symptoms to are overwatering but i've let her soil dry up i want her to get a bit taller before i start flowering her i only have one grow box too so she would have to go into flowering with her sisters which i think i want to start flowering soon since they are already reaching the half way point of how tall i want them to be so idk if i should keep growing her or should i just go ahead and put her in flowering with them anyways? maybe someone can help me out a bit this is my first grow.

Here is what her sisters look like.

the humidity could be too low or they could be rootbound. def keep it up.

Runts can surprise you. I had a plant that, no lie, was over 8 months old and only about 8-9 inches tall, sickly loking, and had only about 6 sets of leaves on it. Kept that thing alive just for the hell of it. And it's not that I did anything different to her than any others, decent soil, 5 gallon pot, right nute mixture, etc. At about mid summer I threw it outside and the natural sunlight and rain just made her take off. She grew to about 5 feet and as of now looks like she'll yield me close to 4 ounces, if not more, dry. Never give up on a plant until it is absolutely dead.

thanks i will definately keep her alive then but should i put her into flowering with her sisters? i only have one grow box, which is my veg and flowering box, at the moment and so pretty much i was planning to put them all in the same stage when they were ready and i think i'm ready to put her sisters into flowering soon.