I have self fertile blueberry (variety name lost) which fruited muchbetter after I bought it a friend. They both spent a few years in pots before I planted them out in the veg plot. I dug big holes about 70cm deep and wide and filled them with ericaceous compost and they've been very happy apart form suffering badly in a couple of nasty winters.
This year we had very few fruits but we had a frost when they were in blossom and that's always bad news. Maybe yours had the same problem.
This year I have given them a mulch of ericaceous compost, added two British bilberries to the same bed, fed all with slow release ericaceous food and done a final mulch of chipped bark. They've all put on good growth and look very healthy so I'm hoping for good crops next year. I shall be erecting a protective cage of fleece round all 4 plants to help keep off winter winds and frosts. Fingers crossed I get no more severe damage.