How to know if AdSense approved or not

It is really unlikely that the Google AdSense is not replying you back. They are very prompt in replying whenever you contact them.
There might be two three possibilities for such a condition.

1.Their response might have gone to your Spam folder.
2. You might not have gone through their guidelines and they don't approve a second account.
3. So, if you are able to place ad in your website, it looks like it was approved somehow.

So to ensure what might have happened, try to establish a contact with their customer care and preserve the copy carefully.

I hope this would let you know about your status.

Google is strict about their customer service. They will definitely reply you either with good news or bad news.

At the approval of your Adsense account you will get congratulatory mail from Google about approval of you Adsense account.

Note : - You will need to place to place sample ad codes on your website/blog before approval.

The thing about adsense is that in order to understand if you are earning from the system, you have to wait for the clicks. Unless the clicks are registered on your system, there is no way to understand whether the account is active or not.

Google adsense forum is active and you can discuss most of the issues on that forum. Just make sure that you read their terms and conditions.

I'd say contact the adsense user forum first. Tell them about your query and ask them where to contact. After that you can try other means of contact. Most of the adsense users can get the support on the forum itself. Another thing is that avoid showing your RPM and account ID using screenshot. This way you don't violate the terms and conditions of Google adsense.