Typically when you use a PGR like chlormequat chloride, placo, etc. early in flowering (first 2-3 weeks) it stops the stretching. When it's used after the significant stretch phase, it bulks the flowers up.
Smaller flowers after use typically could mean the plant was much further from the light than usual, equating to less mass. It could mean the bud got denser, meaning it was visually smaller.
From what I've seen from most people though is that if used in mid flowering after stretch, they get a big boost in flower mass. I can't say the same because the one time I used a PGR through drench it ruined my quality, but I also didn't use it correctly.
Best method of use is to foliar spray at recommended doses the moment you want your plants to stop growing vertically. Even better, anticipate where you want your plants at height-wise and spray when they're a few inches shorter than that.