How do I use TRS matrices in the GL class in loops without it being reset?

I'm trying to create a particle system using the GL class. The only problem I'm having is adding rotation to the mix.

The particles are being displayed properly one-by-one, but when having to display multiple particles; it resets to the newest one.

 public void Draw()
 {
     Matrix4x4 matrix;
 
     GL.PushMatrix();
     GL.Begin(GL.QUADS);
     
     for (int i = 0; i < particleList.Count; i++)
     {
         Particle particle = particleList[i];
 
         if (particle.IsVisible)
         {
             matrix = Matrix4x4.TRS(particle.position, Quaternion.Euler(0, 45, 0), particle.scale);
 
             particle.material.SetPass(0);
 
             GL.MultMatrix(matrix);
             GL.Color(particle.color);
             DrawQuad();
         }
     }
 
     GL.End();
     GL.PopMatrix();
 }
 
 private void DrawQuad()
 {
     GL.Vertex3(-.5f, 0, -.5f);
     GL.Vertex3(.5f, 0, -.5f);
     GL.Vertex3(.5f, 0, .5f);
     GL.Vertex3(-.5f, 0, .5f);
 }

If I put PushMatrix/PopMatrix within the Begin/End methods; then the particles will not display properly.

I have tested placing Push/PopMatrix at different places in the code, but nothing gives me the result I want, so I'm pretty much out of ideas.

I have looked through a ton of information on how to use the GL class, but I have realized that I'm in a kinda unique position here.

If needed, here is a link to the entire file: Pastebin

Any help is greatly appreciated!

-MankeyX