First don't be too hard on yourself, Gardenias are tough to grow indoors as they demand high humidity and soil that is constantly moist but not wet, with perfect drainage. First thing to do is to set your potted plant onto a saucer that is filled with an inch of pebbles. Now add water to the saucer so that the pot sits above the water but is surrounded by water. This will increase the humidity. Mist the foliage several times a day if you can. Gardenias are also happy in a humid bathroom or kitchen. Morning sun is fine but no direct sun on the leaves at anytime or this houseplant may suffer from sunburn. Yellow leaves with light markings are a sign of sunburn. Yellow leaves that drop from the lowest part of the plant are a sign of too much water, too little water or lack of humidity. If the buds fall from the plant (I assume it was in bloom on Mother's Day) that is also a sign of too much water and lack of humidity. Sometimes this picky plant just throws a fit and turns yellow when it is moved to a new location or into a new pot. It's not a very adaptable plant but once you figure out how to make your gardenia happy it can thrive for years in the same pot. No need to fertilize now if you used the Miracle Grow potting soil. Good Luck! Keep growing, Marianne Binetti