Here comes the...first grow

I run my 300w full spectrum LED at 15 - 20cm (5.9 - 7.9 inches) from the top of the tallest plant.. At 10 cm (4 inches) it starts slowly damaging the leaves. - My seedling is around 40 cm (15.5 inches) from the lamp, and not stretching at all. I'd say you could go a lot closer than you currently are, and turn it to full power as well. All you really need to do, is make sure it's not burning the plant, which an LED generally need to get pretty close to do. You can check that by hand. If you can hold it where your plant is, for a couple of minutes, without it starting to feel hot, you're good.

Watering is my first guess, but it looks like you're watering properly based on the absorption pattern I see in your photos. My next guess is that you have given her nutes already. Her leaves are rather dark for a baby. She doesnt need nutes until the round leaves start turning yellow. If it's a premixed composition, all you can do is wait it out. I also noticed you use rainwater. Sometimes this can be way too acidic so you should check the pH. No rash decisions yet, it's just a little drooping, see how she develops.

Young padawan. Your soil mixture should have enough nutrients to get your plant through for quite some time.. Your plant looks heavy and nitrogen saturated.. I recommend you try just water for a weak.,.. Phed or not.. Depending on your soil if it has peat moss in it.. It most likely has an acidic content already which just so happens to be a great thing to grow cannabis in. Pay no attention to schedules in a sense.. there are only guides or outlines.. And they are really aimed at hydroponics or soilless growers. So save yourself a ton of money. use water. Your plant will be happier and you will be as well because she will grow like she is supposed too. Salts in the medium that is rich in nutrients creates a bunch of problems..

looking at these you probably have around 3 weeks left in the grow, if your pushing for 70 days that is a great plan, the plant will be more than ready at that point. if i was you i would start a flush when you get to day 60, at that point doing a 10 day flush would get your girl ready for harvest, your tichomes are what you need to watch, and look more at the buds. these are starting to cloud up and the next stage is amber, looks good, and happy soon to be harvest