Definitely need a pic or two. And I doubt it is as big asw it is going to get; few junipers are normally' small in any way.
You need to get a background fast on basic care (!). Start with www.evergreengardenworks.com/articles.htm and www.bonsai4me.com (dig around) and also the 'stickies' here (top of list of threads, per se)...
It is way too tedious to type out 'basic care', so you have some reading to do
Plenty of credible sources and a browsing of Forums will tell ya what is right -v- wrong. Irrefutable basics are free-draining soil (non-soggy), prudent fertilizing (opinions vary, but in between 'debated extremes' is just fine 99% of time), and that *all* deciduous/evergreen trees must be outside
99.99% of the time. I am in central OK n hour east of OKC and have yet to have any real issues with weather extremes here (with proper precautions, of course). I get MUCH more damage from squirrels (two sapling Japanese maples bitten in half yesterday, one with me standing just three feet away...here we go *again*!
Your jack pines are probably *very* weak from lack of strong sun and not being exposed to the real weather. I am just being bluntly honest; they aren't doing good, IMO. And ithey're also missing out on getting ready for winter so its got a bleak future as it won't handle being indoors much longer. They may pull through, but will be less than what they could've been. I have done seed in wrong seasons as well for the heck of it, but knew that the future was bleak for them when I did it
To have any chance of success, you *must* know what species you have so you know what specific care is needed for that species. Saying some kind of 'Japanese juniper' gets you nowhere really, sorry to say