I think you being married is a big part of the reason nothing is happening.
Let me first say that I appreciate your being honest about it (that is more than SOME are...)

Nevertheless: If a sub is looking for a relationship that is going deeper than some play-only-level, you are not a potential candidate.
The simple reason for this: You are married. Meaning, you already have a "number one" woman in your life.

No sub I met was willing to be the second choice / little accessoire / whatever you may call it.

I, for certain, would not have wanted to be the second choice / the one with less priority than some other woman...

Just my 2 cents.