Hi mommabird -- there are many experts on this forum and I used them last year for a similar project. Many will recommend etching which involves a very toxic application which I wasn't willing to do. If you have a small area, it may be feasible -- this apparently gets you down to the raw, raw concrete and prepares it for anything topical (porch paint, stain, marine paint, etc.).

What I did ... was similar to you ... scrubbed, scraped and cleaned with a degreaser (using brushes in a swirling motion and lots of pressure). I used a Sherwin Williams Marine Paint (two coats) and it adhered just fine. That was a year ago and it is holding up great. Here is an after photo.