[1.8.9] Changing player hitbox glitch

Hey, I'm trying to make the player's hitbox smaller. I already managed to make the hitbox and the rendering (with RenderPlayerAPI) smaller, but when I try to get under one block or when I get at a wall it pushes me away as though I was 2 blocks tall. Does anyone know how to fix this?

My code:

@SubscribeEvent
public void onPlayerTick(PlayerTickEvent e) {
	EntityPlayer player = e.player;
	setSize(player, 0.1F);
}

public static void setSize(EntityPlayer player, float multiplier) {
	float height = 1.8f * multiplier;
	float width = 0.6f * multiplier;

	player.width = width;
	player.height = height;
	player.eyeHeight = height * 0.85F;
	player.setEntityBoundingBox(new AxisAlignedBB(player.getEntityBoundingBox().minX, player.getEntityBoundingBox().minY, player.getEntityBoundingBox().minZ, player.getEntityBoundingBox().minX + (double) player.width, player.getEntityBoundingBox().minY + (double) player.height, player.getEntityBoundingBox().minZ + (double) player.width));

}