IVs and PIDs are unconnected (well, controlled by two different RNGs) in Generation 5; that method doesn't work for deducing your SID from it (excluding potentially using the spots of a Spinda in order to try and identify your PID from there, but too lazy to explain that...).
If you have a Generation 6 game you can transfer any Pokémon (shiny or otherwise, preferably one you don't need back) from your Black 2 save file to your Generation 6 game and send it to one of the many people who can check your SID for you from there.
If/when you have your Pokémon in Generation 6, ask
here to see if someone is free who can check it for you.