Looking good.
For sizing up blueberries, in nursery pots, the recommended soil is a blend of peat, bark & a handful of hardwood sawdust. The sawdust is to feed their endomycorrhiza. The sawdust should be less than 10% of the total mix. 2% to 5% is about right for the sawdust. That is the "nursery pot" soil, for most rapid growth and able to hold enough water that daily watering is not needed.
In bonsai pots, a mineral soil is better, in that the pumice or granite grit will interlock and hold the tree in place. I use roughly a third of the nursery mix with a third of pumice and a third of clay product like haydite or hydroton, or kanuma if I have Kanuma. For bonsai pots this media blend gets sifted while dry, and fines that go through window screen are thrown out.
Keep an eye on watering, an all pumice mix can be too dry for blueberries. Because of their mycorrhiza, they like at least some organics in their mix. It looks like you are using organic cake to feed your blueberry, this may be adding enough organics to get by. So don't do any repotting now just because I offered up mix advice. Think about it for future repots, in 2022 or later.
This will need to grow a year or two before you begin pruning. Chances are fair that middle branch is dead, but you won't know for certain until next summer. Just let it grow for the moment.