I dunno, tough one here.
That plant is super small for being 3.5months old. This plant has been outside for its whole life? It shoud be much more than that pic above, no offense. It should also be in flower lol
Mine in outdoor Michigan began flowering by the second or third week of August. So that plant has been outdoor for months and it should've been flowering for like 6wks already...
Honestly, if you're setting up a space inside then I would just toss this plant and start fresh. I don't think this plant is worth keeping.
But you could totally disregard my message and keep it and put it into 12/12 inside. I still think it'd continue to exhibit slow growth. It's already not worth the time put into it.
I know this post sounds super negative, but I'm trying to be realistic.
Can you post a pic of it now? You said it looks better, let's see. Also, is the inside space done? It's been pretty cold at nights here in my part of MI, outdoor season is finishing up.
I could be wrong but I would just can it and start fresh.