Sorry to hear that Daisysmurf. I too got a cold spell last winter. It killed all growth above ground on my three August Beauties. They are now rebounding but, we are talking about 3-6" tall bushes only.
In your case, if it got cold enough, the cold temperatures may have killed the
flower buds. Another possibility is that the buds survived the ice storm but wild swings in the temperatures later in the
spring caused something called gardenia bud drop. Nothing we can do about those weather related problems, just hope the temps in the Fall allow you to have another set of blooms. It happens here in Texas sporadically.
About the yellow leaves, are the leaves all yellow or do the veins stay green and the rest is yellow?
When the veins stay green but the rest yellows out, you have a mineral deficiency called iron chlorosis. Lowering the Ph of the soil and/or adding chelated products containing iron (available in most 'real' nurseries) takes care of this in a few weeks. Epsom Salts should not be used to address this type of mineral deficiency.
Completely yellow leaves can be some other form of stress or the
plant just getting rid of old leaves.
For example, start by monitoring soil humidity by sticking a finger in the soil or using one of those moisture meters sold at Lowe's and HD. Monitor your soil Ph using and look for any new symptoms. Avoid watering or misting the leaves. Monitor how much sun they are getting; should be morning sun or dappled sun for less than 4-5 hours. Check for insects on both sides of the leaves. Some of these like to cause problems: aphids, spider mites, thrip, scale and mealybugs. While looking for insects, make sure that the main trunk looks fine and has no swollen areas.
I fertilize using a slow-release organic fertilizer called cottonseed meal. I spread 1/2 or 2/3 cup of cottonseed meal to a 2' high
plant around the drip line in March/April and in early/mid summer. As always, water, fertilize and water again.
Good luck, Luis