Mes conditions sont ignorées

Bonsoir,
Voilà maintenant un moment qu'un soucis me tracasse: je suis en train de mettre en place un système d'options pour modifier ses information sur mon site, seulement, quand je valide le formulaire, toutes mes conditions sont ignorées...

Le code:

<?php
$pass = 1;
$avatar = 1;

if(!empty($_POST['a_pass']) || !empty($_POST['nv_pass']) || !empty($_POST['nv_pass_r']))
{
    if(!empty($_POST['a_pass']) && !empty($_POST['nv_pass']) && !empty($_POST['nv_pass_r']))
    {
        $req_a_mdp = $bdd->prepare('SELECT password FROM membres WHERE id = ?');
        $req_a_mdp->execute(array($_SESSION['id']));
        $a_mdp = $req_a_mdp->fetch();
        if(password_verify($_POST['a_pass'], $a_mdp['password']))
        {
            if($_POST['nv_pass'] == $_POST['nv_pass_r'])
            {
                $pass = 2;
            }
            
            else
            {
                header('Location: compte.php?erreur=9');
            }
        }
        
        else
        {
            header('Location: compte.php?erreur=8');
        }
    }
    
    else
    {
        header('Location: compte.php?erreur=7');
    }
}

if(!empty($_FILES['avatar']['name']))
{
    
 $extention = array("jpg", "jpeg", "png", "gif");
 $verif_req_av = new SplFileInfo($_FILES['avatar']['name']);
 $verif_av = $verif_req_av->getExtension();
    
    if(in_array($verif_av, $extention))
    {
        if($_FILES['avatar']['size'] <= 90000)
        {
            list($width_av, $height_av) = getimagesize($_FILES['avatar']['tmp_name']);
            if($width_av <= '800' && $height_av <= '800')
            {
                if($_FILES['avatar']['error'] == 0)
                {
                    $nom_av = $_SESSION['id'] . '.' . $verif_av;
                    
                    $avatar = 2;
                }
                
                else
                {
                    header('Location: compte.php?erreur=6');
                }
            }
            
            else
            {
                header('Location: compte.php?erreur=5');
            }

        }
        
        else
        {
            header('Location: compte.php?erreur=4');
        }
    }
    
    else
    {
       header('Location: compte.php?erreur=3'); 
    }
}

if($_POST['aff_date'] != 1)
{
   $_POST['aff_date'] = 0; 
}

if($_POST['aff_annee'] != 1)
{
   $_POST['aff_annee'] = 0; 
}

if($pass == 2 && $avatar == 2)
{
    move_uploaded_file($_FILES['avatar']['tmp_name'], 'images/users/' . $nom_av);
    if($transfere_av == 1)
    {
        $update = $bdd->prepare('UPDATE membres SET mail = :mail, password = :pass, avatar = :avatar, bio = :bio, opt = :opt WERE id = :id');
        $update->execute(array(
            'mail' => $_POST['mail'],
            'pass' => password_hash($_POST['pass_nv'], PASSWORD_BCRYPT),
            'avatar' => $nom_av,
            'bio' => $_POST['bio'],
            'opt' => $_POST['aff_date'] . ',' . $_POST['aff_annee']
        ));
        
        header('Location: compte.php?modif=4');
    }
    
    else
    {
        header('Location: compte.php?erreur=2');
    }
}

elseif($pass == 2 && $avatar == 1)
{
     $update = $bdd->prepare('UPDATE membres SET mail = :mail, password = :pass, avatar = :avatar, bio = :bio, opt = :opt WERE id = :id');
     $update->execute(array(
        'mail' => $_POST['mail'],
        'pass' => password_hash($_POST['pass_nv'], PASSWORD_BCRYPT),
        'bio' => $_POST['bio'],
        'opt' => $_POST['aff_date'] . ',' . $_POST['aff_annee']
    ));
    
    header('Location: compte.php?modif=3');
}

elseif($pass == 1 && $avatar == 2)
{
    move_uploaded_file($_FILES['avatar']['tmp_name'], 'images/users/' . $nom_av);
    if($transfere_av == 1)
    {
        $update = $bdd->prepare('UPDATE membres SET mail = :mail, password = :pass, avatar = :avatar, bio = :bio, opt = :opt WERE id = :id');
        $update->execute(array(
            'mail' => $_POST['mail'],
            'avatar' => $nom_av,
            'bio' => $_POST['bio'],
            'opt' => $_POST['aff_date'] . ',' . $_POST['aff_annee']
        ));
        header('Location: compte.php?modif=2');
    }
    
    else
    {
        header('Location: compte.php?erreur=1');
    }
}

else
{
    $update = $bdd->prepare('UPDATE membres SET mail = :mail, password = :pass, avatar = :avatar, bio = :bio, opt = :opt WERE id = :id');
    $update->execute(array(
        'mail' => $_POST['mail'],
        'bio' => $_POST['bio'],
        'opt' => $_POST['aff_date'] . ',' . $_POST['aff_annee']
    ));
    
    header('Location: compte.php?modif=1');
}

Seule cette partie s'excécute en ignorant tout le reste:

else
{
    $update = $bdd->prepare('UPDATE membres SET mail = :mail, password = :pass, avatar = :avatar, bio = :bio, opt = :opt WERE id = :id');
    $update->execute(array(
        'mail' => $_POST['mail'],
        'bio' => $_POST['bio'],
        'opt' => $_POST['aff_date'] . ',' . $_POST['aff_annee']
    ));
    
    header('Location: compte.php?modif=1');
}

Merci d'avance pour vos réponses et votre aide !