Add more field to user register form

Hello,

I am trying to add age field to register screen, and I added it to profile field in WP however I still cant post that information to the system from my app and I can show it on the app if I entered it manually to a user, any help please? I know the function the need to edit is public function register() in fluttter-user.php

here is how it looks like after editing but still not working:

  public function register()
    {
        $json = file_get_contents('php://input');
        $params = json_decode($json, TRUE);
        $usernameReq = $params["username"];
        $emailReq = $params["email"];
        $role = $params["role"];
        if (isset($role)) {
            if (!in_array($role, ['subscriber', 'wcfm_vendor', 'seller', 'wcfm_delivery_boy', 'driver','owner'], true)) {
                return parent::sendError("invalid_role", "Role is invalid.", 400);
            }
        }
        $userPassReq = $params["user_pass"];
        $userLoginReq = $params["user_login"];
        $userEmailReq = $params["user_email"];
        $userAge = $params["age"];

        $username = sanitize_user($usernameReq);

        $email = sanitize_email($emailReq);
        if (isset($params["seconds"])) {
            $seconds = (int)$params["seconds"];
        } else {
            $seconds = 1209600;
        }

        if (!validate_username($username)) {
            return parent::sendError("invalid_username", "Username is invalid.", 400);
        } elseif (username_exists($username)) {
            return parent::sendError("existed_username", "Username already exists.", 400);
        } else {
            if (!is_email($email)) {
                return parent::sendError("invalid_email", "E-mail address is invalid.", 400);
            } elseif (email_exists($email)) {
                return parent::sendError("existed_email", "E-mail address is already in use.", 400);
            } else {
                if (!$userPassReq) {
                    $params->user_pass = wp_generate_password();
                }

                $allowed_params = array('user_login', 'user_email', 'user_pass', 'display_name', 'user_nicename', 'user_url', 'nickname', 'first_name',
                    'last_name', 'description', 'rich_editing', 'user_registered', 'role', 'jabber', 'aim', 'yim',
                    'comment_shortcuts', 'admin_color', 'use_ssl', 'show_admin_bar_front', 'age',
                );

                $dataRequest = $params;

                foreach ($dataRequest as $field => $value) {
                    if (in_array($field, $allowed_params)) {
                        $user[$field] = trim(sanitize_text_field($value));
                    }
                }

                $user['role'] = isset($params["role"]) ? sanitize_text_field($params["role"]) : get_option('default_role');
                $user_id = wp_insert_user($user);

                if (is_wp_error($user_id)) {
                    return parent::sendError($user_id->get_error_code(), $user_id->get_error_message(), 400);
                } elseif (isset($params["phone"])) {
                    update_user_meta($user_id, 'billing_phone', $params["phone"]);
                    update_user_meta($user_id, 'registered_phone_number', $params["phone"]);
                     update_user_meta( $user_id, 'age', $_POST['age'] );
                    
                    update_user_meta($user_id, 'age', $allowed_params["age"]);
                    
                }
             
            }
        }
        wp_new_user_notification($user_id, null, 'both');
        $cookie = generateCookieByUserId($user_id,  $seconds);

        return array(
            "cookie" => $cookie,
            "user_id" => $user_id,
        );
    }