my blueberry bushes are doing strange things

hi all is it normal for a blueberry to have its main stem long and straight or does this signify it needs to be re-potted? it is in a 12" x 18"pot at mo the main stem is a good 15 inches taller than the rest of the plant

Will get different growth habit with varieties, there are these dwarf bushy ones, too, nowadays, but mine are more like a raspberry and should branch naturally, all pruning needed is to remove old shoots at ground level every 2-3 years.

Don't think you need pottong on at all.