Is it possible to check is loaded language files correctly with WordPress plugin?

I have a plugin to be translated. I have done following tasks:

1. Loaded the TextDomain

$my_td = 'mysignup';
function my_signup_textdomain_init() {
    load_plugin_textdomain( $my_td, false, dirname( plugin_basename( __FILE__ ) ) . '/languages/' );
}
add_action('plugins_loaded', 'my_signup_textdomain_init');

2. Added language files(po, pot, mo) in wp_plugin_folder\my_signup\languages (for Bengali bn_BD)

• mysignup.pot
• mysignup.mo
• bn_BD.po
• bn_BD.mo

3. Changed the language code in wp_config.php file

define('WPLANG', 'bn_BD');

But the problem is nothing is changed. I am not sure what I have done wrong.
Now I need to know how can I test everything, whether what I’ve done is fine, and how can I solve the issue.

For plugins using the directory referred to by load_plugin_textdomain, the language files should be named “domain-locale.mo”.

So for your case, the filenames should be mysignup-bn_BD.mo.