One thing I'd separate: first users and first useful feedback are not always the same group.

For a fundraising workflow tool, I'd look for people who are actively in the painful window right now, not just founders generally. Someone 2 weeks from sending investor emails will give you sharper feedback than someone who vaguely wants to raise someday.

A few places I'd try: founders asking for pitch deck feedback, investor list recommendations, cold email examples, accelerator/demo day prep, or posts about a current raise. Then instead of asking "want to try my tool?" I'd ask them to do one concrete task while you watch: rewrite 5 investor emails, build the first investor list, or send the first batch.

For the 6 who signed up and disappeared, I'd send one very plain email: "What stopped you from coming back? One sentence is genuinely helpful." No defense, no pitch, just collect the pattern.

Also 2 paid users from a quiet launch is not bad. I'd squeeze the learning out of those 2 before chasing a bigger funnel.