At my wits end growing revenue for boutique research firm

Long story short: my partners and I launched a sell-side research firm targeting large hedge funds and some long only shops. We've grown our client base to about 50 and our clients are very engaged and they're all paying as promised, but I am frustrated at our growth rate. We're growing clients and revenue at about 20% yoy, but we're struggling to top $2m in total revenue. I'd like to grow to about $7-8m in revenue, but it just seems impossible. Is this an unreasonable amount to expect for a 5-person firm? Any suggestions on what we could do to reach new clients and/or get more votes/dollar commitments from current clients? I've been considering hiring more people to launch new research coverage as a way to extend the company, but I don't know if that's the way to go in a post-Mifid II world where small research shops are increasingly associated with delivering one very specific thing.