Q.Why Were The Good Night KISS Blossoms Get So Small?
I had two plants of Good Night Kiss. One was normal sized blossoms approximately 2” diameter. The other plant to blossoms were half the size. Ever blossom on the plant is miniature and continues to be so. Both fertilized the same, watered the same, same soil.
Certified GKH Gardening Expert
Unfortunately, your photos did not come through.
Depending on the type of fertilizer, it could contain too much nitrogen and not enough phosphorus and potassium.
This article will help you to understand the care that these plants require:
https://www.gardeningknowhow.com/ornamental/flowers/million-bells/calibrachoa-million-bells.htm