So some basic advice that I can give you:
If you are familiar with torrenting, and you would like to actually know whats goin on in your soil and how to achieve the perfect balance of fungai and bacteria then Teaming with Microbes is the book for you. If you want to buy the book legally then you can just order it online. It's kind of like a textbook, so it isn't the most enjoyable read. But the knowledge you gain about soil is priceless. I personally think Jorge Cervantes is full of shit and I'm almost positive he doesn't grow, so I wouldn't trust his book. But that is my opinion.
As far as watering goes you need to understand why we water, and what happens when we do. Watering makes the nutrients that exude from the dieing microbes possible to be sucked up by the roots. However, over watering prevents any oxygen from getting to the roots and halts the process completely. You need to find a balance when you water, and you need to do it regularly. By this I mean that plants prefer to be watered on a schedule. You should also get into the habit of large waterings that cover the entire pot. The way that roots expand is that the soil dries up where the roots have been sucking up the water and nutrients and they expand throughout the soil in order to find new nutrients. So you actually would like your pot to appear dry. This allows the roots to search for water throughout your moist soil. This is also why you see lots of growers using peat moss/lava rocks/perlite, whether they know it or not, they are extending the dry period between waterings which provides for more root growth.
Why is root growth important? Look up apical meristems. They control the way a plant grows, and if you notice, the growth of the RAM (root apical meristem) is directly connected to the growth of the SAM (shoot apical meristem). What does this mean? Good roots = Good plant. Plain and simple.
You can run an entire indoor grow without a single nutrient, just base soil, and you will have good results. I recommend this for your first grow, but if you want to mix it up feel free. Just realize that it's not the nute company or the amount of nutes you put in that's important. It's the balance of nutrition. The most important part about growing is understanding that balance is everything. That's why a good quality base soil is all you need. It is incredibly balanced and packed full of nutrition. If you would like the science behind a good balance: basically the roots have a bunch of hydrogen on them which is a cation. They exchange their hydrogen for a cation that is hanging out in the rhizosphere, and get nutrition off of it. If there are too many cations to exchange though, those cations just hang out in clusters. The cations on the roots attract anions as well (basic chemistry here) but what does not get attracted falls to the bottom of your pot and forms a salt build up similar to the salt clusters left behind by the excess cations. This is why lots of growers need to flush, there's a shit ton of salt hanging out in the bottom of their pot which will cause "nute burn" which is really just too much salt. As you can see, if you are using a nutrient that uses way too many cations and not enough anions or vice versa or too much of both then you are going to end up with horrible results.
More is really less with growing and that's why everyone says KISS, but rarely anyone follows. Note that weed has been able to grow by itself for 34 million years. Killing a plant usually has nothing to do with doing too little. It's almost always because you are doing too much.
You already seem to know how to keep a balance climate, which is 75% of indoor growing, so you're good there.
Edit: Also, your plants are still super young, just water them regularly with big waters and lots of space inbetween (I water my seedlings once a week for week 1 and 2). And any problems they have they will fix themselves, so long as your climate is ok. Once they get bigger and you see more issues then you should start worrying about what's going wrong.