Lilac

Your plant’s foliage does look like a Lilac, but we can’t be sure without seeing flowers, the same problem you are having since it has not bloomed for you. Lilac produces fragrant trusses of flowers in blue, purple, pink, white. Most require winter chill and this might be the problem in your zone. There are some such as the Descanso hybrid lilacs that have been bred for the moderate temperatures of Southern California, but if yours is a chill-required variety, chance are slim that it will bloom. All lilacs need full sun or where summers are hot, light shade and regular water. Prefers well-draining neutral to slightly alkaline soil. If you do get it to bloom, prune just after flowers are spent to encourage new shoots and better flowering for the following year. Feed with a slow release or organic fertilizer formulated for blooming shrubs about once a year just as the buds are beginning to emerge.