Gardeners learn patience with lilacs. They believe in no bloom before it's time and like to be fully mature such as at least 7 years old before putting out the energy for lots of flowers. Lack of sun can also contribute to low blooms on a lilac. There is a lilac called 'Miss Kim" that is a dwarf (still getting 5 feet high) and it tends to be a heavy bloomer with repeat flowers. If your lilac is partially shaded move it to a full sun site with good air circulation. Lilacs transplant easily in the winter when the ground is not frozen. If your soil is naturally acid (for example you live in an area of high rainfall) then add a cup of lime around the base of your lilac this fall. Remove all faded flowers and don't let the lilac shrub suffer from lack of water late in the summer when it is setting buds.  Hope you'll smelling that sweet lilac fragrance soon. Keep growing, Marianne Binetti