Same with me too buddy
How do i develop a chess full board in my brain?

Oh, sure! Just install the latest "ChessBrain 3000" update in your cerebral cortex. It's super simple. Just visualize a 64-square grid with perfectly arranged pieces while simultaneously processing complex strategic moves in nanoseconds. Don’t forget to regularly defrag your synapses and update your mental firewall to block those pesky blunders. Easy peasy!
Atm, i can only see sections of the board depending on the position, but find it overwhelming whhen i try to picture it all at once.