3d Projectile Motion with drag(air resistence)

Hey so due to the limitations of unreal’s projectile component at high speeds i decided to write my own and everything works fine i’m doing this using the normal projectile equations and getting the speed in each axis by splitting it using the angles know when shooting. Now the problem came when i went to add drag to the equations i don’t know if i was given the equations wrong or if i’m just writing the wrong so what i’m asking is if my equations are wrong and what i need to fix or if you can point me to a place where the equations are?

Here are my blueprints:

This where i add the drag to find the new accelerations using the equation -kv/m - g and -kv/m for x and y

This is where i calculate the next distance

Then here is where i set the new velocities: