I need help finding my target audience (I will not promote)

I know, I made #1 mistake of SaaS building - find target audience before making anything. At first the project started as in-house project 2 and a half year ago for a company that works in Online Ad space. After 5 months of in-house development I've left the company and ever since have bee building my product. I've gotten really far. Very close to MS full certificate far. (if only the final report wouldn't take 5-10 business days after I already know the pen test is done). I don't want to jinx it.... Anyway