Q.Why Are Our Lilac Bushes Not Producing Larger Lilacs?
Why are our lilac bushes not producing larger lilacs? They get lots of full sun. I believe we keep them quite moist (watered). We have clay soil so usually on our property water hangs around. These bushes were planted 3 years ago. it seems like year #1 they did well, but last year and this year the actual flower is small. The green folage is very nice. I’ve attached a photo.

Certified GKH Gardening Expert
Those look like dwarf Korean lilacs and they are a little different from other lilac shrubs. They stay smaller and the flower clusters are smaller, but more numerous on the shrub. Your photos just look like the buds. They don't look like they have opened. Was there a late freeze that zapped them? The soil may be a problem. They need well draining soil. Side dress the shrubs with peat moss, compost, or other soil conditioners and lightly rake it in. It should eventually filter down into the soil and improve it.
https://www.gardeningknowhow.com/ornamental/shrubs/lilac/dwarf-lilac-varieties.htm
https://www.gardeningknowhow.com/ornamental/shrubs/lilac/common-lilac-problems.htm
https://www.gardeningknowhow.com/special/organic/how-to-easily-improve-your-clay-soil.htm