Hmmmm.... What you’re describing with the leaves getting smaller kind of reminds me of something that I noticed with my Rubber (tree?) plant - but in reverse.

I had it at work & since my office is an internal one with no windows to the outside, I got a blurple grow light that was on for 8 hours a day. It survived but never really flourished. The leaves were very small.

Well, I brought the plant home & put it near a south facing window. What I noticed is that it’s really flourishing now. All kinds of new growth and the new leaves are 2-3 times the size of the older leaves. The funny thing is I’m sure the leaves were big when I first got the plant, but the transition to the smaller leaves was so gradual I didn’t even notice it until I brought it home and recognized that the plant was changing. I guess the size of the leaves were directly related to how much light it was getting. Less light so no need to waste energy producing bigger leaves...?

Just thinking that while the grow light helped to keep my plant alive, ultimately the natural light has helped it to thrive. I changed nothing else.

Maybe something similar is going on with your plant.

Here are a couple of pictures of the leaves. There are several plants in the pot. These 2 leaves are from the same plant. The small leaf is older & lower down on the plant, grown under the grow light. The larger leaf is higher up and a newer leaf grown in bright filtered light (in a window through the screen). For reference my hand is about 9 inches long. Some other plants in the pot have larger leaves that what I’ve shown here.

Thank you! I’m going to try and give it the most natural light I can. I have it in my bedroom and I only have one east facing window. I think I’m going to put up a hook and hang it so it gets the morning sun! I really hope that’s the only problem because I really love this plant! I had it under a grow light because all my other plants love the grow light but for some reason this one doesn’t. Thanks so much for your help!