You're lucky it hasn't fallen over yet, that little sprout is stretched. You need some support around that stem pronto.
The sunlight during winter isn't enough to raise a plant on. You need a light if you want it to grow at a normal rate. No amount of chemicals or water will make up for lack of good lighting.
If you can't give it a grow light, (there are florescent bulbs that could do the trick), you could just put up with the slow growing until spring, and it'll start growing just like everyone else's. IT'S NOT THE PLANT'S FAULT. Nor is it your fault, you just started growing at the wrong time of year.
Also, What are you going to do once it becomes a recognizable marijuana plant? How often does your dad come into your room?
How much money are you willing to spend?

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