Text alignment in OpenGL with FreeType2

Question

I'm trying to implement font rendering and have got into some trouble with glyph metrics. Here's the code where I get the metrics:

Glyph gl;
gl.width = face->glyph->metrics.width / 64;
gl.height = face->glyph->metrics.height / 64;
gl.character = i;
gl.advance = face->glyph->metrics.horiAdvance / 64;
gl.bearingX = face->glyph->metrics.horiBearingX / 64;
gl.bearingY = face->glyph->metrics.horiBearingY / 64;
gl.textureX = this->_textureWidth;

The value of gl.advance is way too small. Here is a picture of it:

If I'm dividing face->glyph->metrics.horiAdvance by 40, it looks like this:

The text is now readable, but the advance and X-, Y-bearing still don't look correct. This is what it should look like:

Here is my code where I draw the glyphs:

float aspect = this->_graphics->getMetrics().x / this->_graphics->getMetrics().y;

float offset = 0;
for(unsigned char c : str){
    Glyph g = this->_fonts[fontID]->getGlyph(c);

    vec2 pos = (position.getRelative() + vec2(offset, 0) + (vec2(g.bearingX, -g.bearingY) / SCALING) * scale - vec2(1, 1))
                * vec2(1, -1);
    glyphShader->setUniform("position", pos);
    glyphShader->setUniform("scale", (vec2(g.width, g.height * aspect) / SCALING) * scale);
    glyphShader->setUniform("glyphSize", vec2(g.width, g.height));
    glyphShader->setUniform("textureMetrics", this->_fonts[fontID]->getTextureMetrics());
    glyphShader->setUniform("textureOffset", vec2(g.textureX, 0));
    glyphShader->setUniform("image", 0);
    glyphShader->setUniform("color", color);

    this->_graphics->getMeshByID(guiInstance->_quadID)->drawMesh();

    offset += (g.advance / SCALING) * scale;
}

I'm doing some transformations on position to move the origin to the top-left corner and flipping the coordinate system on the X-Axis. Then I divide every pixel value by a constant factor, to have the font having the same size on every resolution. The ratio of the glyphs is correct, but not the alignment. And here is my vertex shader:

#version 400

layout(location=0) in vec4 vertPosition;
layout(location=1) in vec2 vertUV;

uniform vec2    position;
uniform vec2    scale;
uniform vec2    glyphSize;
uniform vec2    textureMetrics;
uniform vec2    textureOffset;

out vec2 fragUV;

void main(void){
    gl_Position = vertPosition * 
                  vec4(scale, 1, 1) + 
                  vec4(position, 0, 0);

    fragUV = vec2(vertUV.x * (glyphSize.x / textureMetrics.x) + (textureOffset.x / textureMetrics.x), 
                  -vertUV.y * (glyphSize.y / textureMetrics.y));
}

Why are the characters misaligned?