I'm going to go respectfully disagree with the others, and suggest that sterilization is not the problem - what you describe should be more than adequate. The problem is 1) wild blue mold is everywhere, and is very aggressive, and 2) you didn't "out-compete" the wild mold with the desired mold.
Keep in mind that, unless you make cheese in a bio-filtered clean room, you cannot escape wild mold and bacteria, present in the air, from getting to your cheese at every stage of the process. One second after your utensils have cooled down from boiling or dishwasher or anything else, they are now becoming infected. While you are gently heating the milk, all sorts of mold and bacteria are finding their way to the surface. As you mill it into curds ... you get the idea.
As I understand it, sterilizing IS important, not because it eliminates any of this wild air-borne bacteria/mold from getting to your cheese, but rather because 1) it eliminates contact-borne nasties like E. coli, and 2) it keeps the undesirables from getting too strong a hold up front. You want to give room for the desired bacteria (and mold, if that is part of the make) to take hold and develop, so that they can out-compete the undesirables. In other words, if you start out with the undesirables "in control," your desired bacteria/molds are going to have trouble doing their job.
As for the mold inside your second cheese ... mold DOES require oxygen, regardless of whether it is wild or domesticated/desired. So the only way the interior of your cheese developed so much mold is that there were sufficient gaps and cracks between the curds to allow it to develop. In a typical blue cheese, piercing reinforces what should have already started with the gaps and cracks, allowing more oygen in for more development. And again, wild blue is EVERYWHERE, and it is super aggressive - and by the time your cheese is sitting in the cave, sterilization is long since past.
All that to say - get thee to a cheesery and buy some P. Roqueforti! I buy most of my supplies on-line from Artisan Geek, and there are several other good vendors. The P. Roqueforti may seem expensive up front, but a little bit goes a long, long way, so it really is very inexpensive on a per-cheese basis.