Catnip tips? and growth pattern question

[Chimetals]

After the deaths of a few store-bought catnip plants, my parents mail-ordered me some seeds for Christmas. I left most of the sprouts at home (why I thought planting 100+ seeds in two 3" pots was a good idea, I still don't know) and brought the most developed plants back to campus with me.

I was wondering if there were any ways to spoil my catnip plants more, and if I need to pluck them more or not. If it matters, the window I'm growing them in is west-facing, and I'm a heavy tea drinker, especially mint tea, though I'm otherwise limited as far as possible fertilizers go--I am sharing a room with these plants, so I can't have anything rotting in there, lol.

Also, I've noticed that despite being from the same seed packet/bred strain, my two largest plants have taken on different growth patterns--one seems to grow shorter, with well-defined veins on its leaves, and the other has grown upwards more, with flatter leaves. Are they secretly from different plants, or are the pots/foot difference on the windowsill able to affect their growth this much?

pictures:

[shadylane]

your catnip looks good, and keeping it in your window catnip does well in sun or shade. Catnip does well in almost any good soil but it will be more fragrant if grown in sandy rather than in heavy soils.
They will need to be thinned eventually....

[Chimetals]

thinned, like separating plants? because each pot only has one plant D:

I've been pinching off the new growth to make it branch out like crazy, though. I'm just not sure if I'm pinching an ok amount off, or if I should do more.