Lilaeopsis troubles in my fluval edge. Please see pics, help!

[Yianni]

OK, so I have a fluval edge. Already that is a huge challenge for many things. I have done DIY light mod, simply changed the bulbs for 2x LED 2.1W MR11s, and added 2x small LED bars which apparently have 3W each. It is literally all I can squeeze in the small compartment at the top of the Edge. So for a 6G tank, I have about 10Watts. I know it is not enough, but it is as far as I can go for it to be aesthetically pleasing to look at. I have a CO2 tank, and the diffuser is at the bottom of my filter! I tried everything to make it clean-looking.
For the substrate, it is a black gravel superior substrate (no idea if it is good enough for the plants, but the store did not seem to have anything else but normal rocks besides that).
I planted little grass-looking plant. I am not sure if it is lilaeopsis mauritiana, or micro-sword. But before I got the additional light bars, they had stem rot going on. I unplanted everything, cut out all rot from EVERY ROOT (i swear to god), and replanted them all dead-center under the light fixture.
I fertilize with the bottom of a Flourish Excel cap daily, and put about the same amount of FLOURISH except weekly and maintain PH toward the neutral (tends to naturally go towards 7.6 when I do a water change).
There seems to be some form of light-brown mossy looking residue (VERY SUBTLE) that seems to be forming on top of the grass, but they still look pretty good. Please help identify and tell me what on earth I am doing wrong. I tried really hard to make this planted tank a success and if all else fails, I might throw in the towel and stick with fish. I seriously have overcome a lot, from the LPS selling me non-aquatic stuff that filled my tank with pond snails... Not having the heart to kill living creatures, I bought another Edge (not from that pet store) and put the snails along with my betta and neon tetras (there are now nearly 50 snails in the other tank!)
Is the problem my gravel substrate? Is it the lack of light? (I have seen videos of people who claim their stock lighting was enough for plants if kept in middle of tank under lighting, and frankly, I probably have like 8 watts more than them)? Is it my fertilizers? Should I change how much I put? I heard some grass are more Root feeding and some have recommended tablets I think. Should I put that? Any input appreciated. I added 3 pics and can add more if you need more details.
oH and there are 2 shrimp in there too. Have had them for about a year.