Hi Tom, welcome to the community! I don't think you're barking up the wrong tree at all. Building a business takes time, especially when you're working with a limited budget. It sounds like you already have something that's incredibly valuable—happy customers who appreciate your quality and craftsmanship.
I'd continue asking satisfied customers for reviews, photos of completed projects, and referrals while you build your online presence. I'm also interested in hearing what has worked for other members when it comes to growing through Facebook Marketplace or creating a business page. Wishing you the best as your business continues to grow!