I complete demo and achievement doesn't work :c

Can you make a difficulty where i just shoot the enemy with infinite bullets or it has a manual reload function. I find the current gameplay mechanic of dashing to get bullets not good for me. Specially since i feel like i don't have enough HP so i will have to play perfectly just to beat the boss but i want something that is still hard but more casual then full on difficulty. I understand the game was designed this way but i am not sure if you can make it more hard but still casual mode for the game or so...