I've just checked online for this plant, to be faced with various florid descriptions, one of which ended with the immortal line "keep in a suitable pot, and you will have a marble for your sitting room". Presumably they mean marvel...
Anyway, first let me say it's always best to listen to yourself instead of your boyfriend, and second, a better food for this plant would be something like Baby Bio, which is a specific houseplant food and good for foliage plants. I don't know which Miracle Gro you've been using, but the formulation is likely to be incorrect for this plant. If you think the pot is too large, turn the plant out and check what the roots are doing - it would be better potted into the correct size if there's lots of loose compost when you do turn it out.
This plant hates draughts and sudden changes in temperature - even indoors, mine sulks a bit and drops leaves around now and in Spring, when the seasons change. Likes a bright light, but not sunlight, keep away from radiators or heat sources, and not in the space between, say, a window and a door, where it may feel draught. Also inspect the leaves, stems and branches, and the compost you empty out, for signs of infestation or disease.

Thanks Bamboo. I've been to the sitre that says marble for your sitting room lol. It is growing well. I just wondered if anyone had any tips on getting it back to it's original bushiness.

Sue