Blueberries like a deep, rich, well draining soil. They like to grow with around 6 hours of sun.
They need a soil acidity of around 5.2 -5.8.
I planted mine in deep, wide holes. The hole was as deep as the nursery pot and twice as wide. I backfilled with an equal mixture of soil, peatmoss and potting soil with a half cup of Hollytone. I have since ordered a soil acidifier.
After planting I got about a dozen blueberries last year on five plants. This year see image.
This year my 5 plants have about 300 berries on them.
So instead of answering your question, I told you what I have done in 14 months. Evaluate what you are doing and compare. I think that you will gain some valuable insight!