There are two kinds of hosting you are talking about, so let’s clear that up real quick:
- Bluehost, et al., are web hosting companies.
- DigitalOcean is a virtual server hosting company.
So your blog is fine at a web hosting company, but Discourse requires its own server. It is technically possible to host all your stuff on a server at DigitalOcean, but it is not practical, especially for your use case.
That means you will need web hosting for your blog, and separately a server for your forums. It is more expensive, obviously, but getting started you can get both for $10 or $15 a month, each.