I planted a little ugli fruit tree by seed a while ago and it has lived perfectly fine for 2+ years. (Surviving through New York's winters inside.) However, just recently a few leaves fell off and I thought somehow the wind was too rough and it blew through the window, knocking off some leaves. But every other day one leaf fell off. And slowly but surely my ugli fruit tree lost all of its leaves except for one so far. (Which can fall off at any moment now.) I have read into how temperature fluctuations are the main cause of this but I keep the plant inside at a constant 70ish degrees. And it's summer anyways, it does not get very cold at night at all. One more thing, as you can see in the picture, where the leaves used to be, there are now tiny leaves. Are these replacing the original ones and will they keep the whole plant alive long enough till they grow more? Any help is very appreciated.