I'm not sure but google Serissa and see if this is what your tree looked like before, well, now 0_-

Antoinette

I'm no expert, but it looks like a form of boxwood. I often have leaf loss as well when my plants are stressed, often because of too much or too little water. You may want to check the roots to look for air pockets or soggy areas causing root damage.

This is a Fukien Tea.

Watch your watering with it, especially in that peaty soil. It will hold water for far too long and cause your leaves to yellow. Make sure you give it as much sun as you can, as these will gladly take it. They're rather finicky, so be prepared for much more leaf drop, unfortunately.

hi AK
no offense, but how do you go from 'high water' to 'low water' in a matter of ('maybe two weeks')?

Ive have one a little smaller than yours on my (east facing) bath window for about 3Mnths now, hasnt grown an inch that i can tell, but i allow it to become fairly dry between waterings.
In that (your) soil, when bone-dry, it should 'feel' almost feather light, see?
You have to get a feel for that, untill you do, you'll need a way to check it, particularly the bottom of the soil/rootball, not just the top inch, dig?

I would consider pulling it out of the pot (it 'should' stay together, intact,, you'll know) and seeing just how dry, moist, or Wet it actually is (in its entirety) or, you could get a dowel stick of some sort, poke it (deep) into the soil, leave it for a cpl mins, and learn to judge from that,,,

'Most' plants dont like to be constantly 'wet',, OR moved constantly while theyre trying to acclimate to a new environment (your home), from what mayve been a semi-temporary environment anyway (this campus today, another tomm, gotta sell these tress,,,).

Carmona microphylla, Fukien or (Fuijan) Tea are even a little more sensitive to this, as Ryan says, their 'rather finicky', or can be,,
In the heat of my Apt, in dead summer, i doubt i watered twice a week.
...not saying to compare your situation to this, but its hard to imagine all the 'trial n error' you described, (4 waterings in 2 weeks vs. xxxx....). Outside in Full Sun, it might need waterd daily, inside, in filtered/dappled/indirect light probably mush less,, the key is to match its watering NEEDS, to the amount of light you can give it. NOT 'its wed., or 'looks' dry, time to water', not saying You do, but some do,,,,

Yellowing leaves are typically an indicator of a watering issue, or somtimes just any 'stress',, (unfortunately) it could indicate too little, or too much,, but thats your first 'clue', its talking to You, you just need to learn to 'listen'.

If its been seriously water-logged for a significant time, you may need to allow it to dry out more than you probably think, (just not Bone-Dry), kinda 'weening' her back like, ya know?

...would really need to 'know' whats going on below the soil line,,,
btw many plants will 'tolerate' a variety of conditions, beyond what they actually 'prefer', but ya gotta kinda allow them a minute or two to adjust to it, hopefully we're not at a point where we cant give her another minute to adjust,,,

heres some 'general' care tips to start ya off
http://www.bonsai4me.com/SpeciesGuide/Carmona.html
http://www.bonsaigardener.org/fukien-tea-bonsai.html

Shes a cute little specimen! hope ya can get er goin, post back if ya want or (need?) to
I'd luv to hear how shes doin, regardless...
Pls know that (despite however it 'sounds' whilst i hastily typed, with nothin but dinner, a shower, and My plants needs being backburnered in mind...) im really hoping this helps some, else i wouldnt have bothered right? :)
ss

nice nick btw :)

I know it's been a while, but thanks for the help everyone! Especially SS and Ryan. I'm 90% sure this is a Fukien tea now, and your information and suggestions have helped a lot.
While I haven't been able to stop leaf loss completely, it's been losing a lot less, and I've even seen some new ones growing. So hopefully, I'll be able to keep this one for a while.
Thanks again!
AK