Hey Rob, it is certainly possible for you to bootstrap a successful SaaS. Without money to pay a developer, though, your best bet would be to learn to code yourself enough to put out a product to test the waters. Once that gains some traction, partnerships and funding would be easier to come by. That path would probably eat up 3-9 months given the bulk of your spare time and energy.
Why do you think you want to build a SaaS product though? It seems to me like you're already putting out content pretty regularly. I would recommend moving it off medium to a domain you control and start getting some emails for your list. You can still publish there, but link back to your own site. With an email list, your readers can turn into your customers. As a designer, you can then start building products like books, courses, podcasts, guides you name it which will let you take advantage of the skills you have already. Check out Design for Hackers, for example. Why not use the edge you built up instead of starting at a disadvantage?
Why do you think you want to build a SaaS product though? It seems to me like you're already putting out content pretty regularly. I would recommend moving it off medium to a domain you control and start getting some emails for your list. You can still publish there, but link back to your own site. With an email list, your readers can turn into your customers. As a designer, you can then start building products like books, courses, podcasts, guides you name it which will let you take advantage of the skills you have already. Check out Design for Hackers, for example. Why not use the edge you built up instead of starting at a disadvantage?