Wow, great success story. Some kind of echeveria?

BTW, are the leaves supposed to grow upwards, like in the first photo (before potting)? Currently, the older leaves are more horizontal than upwards. Is that normal or am I underwatering or is it some other problem? The container is shallow (~1.5" high) and I tend to let the potting mix go dry because I'm very worried about overwatering. On average, I think I water every 7 to 10 days.

I don't have an outside. I only have east-facing window stools. This Echevaria is together with other succulents under a grow light. So, it appears, my grow light is not enough. It's just 18W.

18W is not a problem, what matters is how many kelvins and lumens your light supplies.

Agree with Kara it being E. agavoides, and also about flatenning and/or recurving leaves.

Hmmn, good point. I know what K I get when I buy my regular bulbs because I almost always choose 4000 to 6500K.

But the grow lights I have are those gooseneck dual lamps with alternating blue and red LEDs (460, 660 nm) per lamp. I use both, full intensity (100%). Specs say 576 lumens.

576 l sounds quite low to me. I have LED tubes that are 12W, 5000k and 1550lumens (mostly using for haworthias); and also 18W, 6500k and 1800 lumens (I use 2 tube, 4' long light fixture for most succulents). Just regular lights, no 'fancy' red and blue. But I am no expert, so wait until someone else comments.