If you're not getting the replies you want on OKCupid (the most poly-friendly dating site I know of, and where I found 2 of my 3 boyfriends), then perhaps instead of searching elsewhere you should look at the impression you're making with how you're advertising yourself.
In the other thread you started
here, you say you're looking for a "single/straight man to join our relationship long term" rather than a "man open to forming a long term relationship with a happily married woman".
The second version makes it reasonably clear that your hypothetical single/straight guy (SSG from here on) will be entering a relationship with a woman, whereas your version lumps you and your husband together as a single relationship unit, thereby insisting that by being in a relationship with you your SSG will also be in a relationship with a man - your husband. If SSG is entirely straight (as you've specified he must be), then that may be an immediate turn off, even if only on a subconscious level. If he's only
mostly straight, then your following paragraph with the line "NOTHING sexual and definitely not bi-curious" will reek of biphobia and be an immediate turn off. Congratulations, you've just repelled 100% of your target audience.
Your choice of language: "add to our current relationship", "join our relationship", "looking to add", etc, lead me to believe you might benefit from reading up on couple privilege. I realise you're looking to form a V rather than a triad, but
So, somebody called you a Unicorn Hunter? would be a good place to start, followed by extensive Googling on the subject. Using "our" rather than "my" and "us" rather than "me" is a red flag for couple privilege and would probably cause anyone familiar with the idea to shake their head and click away to the next profile.