Do you just want that person to wear a diaper in front of you, what do you want them to do? Is it just the diaper or would you like to be a parent figure also? Finding someone with similar interests would be perfect, but there are ways around that. You could find someone who will fulfill your dreams even if it is not their thing, but you would need to be open to making their dreams come true, just as they did for you. A fetish quid pro quo. But that will require putting your desires on the table in front of some people, which will open you up to rejection. I feel like as much as it sounds like you long for this type of play you would be doing yourself a disservice by not fulfilling your desires.