First and foremost, the tree has been in your care for 4 months, and it is still alive. And you are already doing your best to understand its needs. I’m betting on that tree to be alive and very well in another 4 months, now that you can give it sunshine — even if you do have to move it in & out for a bit longer.
I have only tiny serissa plants, and tiny experience — I ordered them online, and then wondered what I’d let myself in for — but they’ve tolerated shipping (from Ohio to Florida), and being brought inside the house as we had a late “cold snap,” out for sun, and then into the unheated utility room overnight, and they haven’t seemed to care as long as they get some sun. Currently, I give them morning sun on the east side of the house, and afternoon sun on the west. And I’ve gotten bold enough (given that Florida sun) to give each a fair slosh of water in the morning (provided I’ve felt dry soil most of the way down) and check again in the evening. So far, so good, although I’ll be vigilant as the daily temperatures rise.
Read MellowMullet. You’ll be able to relax a bit — and you’ll have someone to call on. I expect to hit him up with questions myself.
Best wishes for continued success!
— Amy