Eventually, I figured out a different solution.
Before messing with parabolas on 3D I did the same with Lines, and unlike Parabolas, lines do have a vectorial equation. I made a line equation with an addition with a max height (for apex point).
Then I calculated the apex point using that height, calculated the A B and C values of a parabola that would contain those 3 points, calculated the trajectory as for a linear equations, only changing the Y value based on the parabola’s
It created a perfect parabola that is defined by a start point, an end point an apex height