A picture of your floors would help everyone a lot.

I painted oak floors in a breakfast nook. Light blue/grey from a "porch" line of paint by Rustoleum. It held up well for many, many years.

Here is a link to Bob Vila advising how to paint a wood floor: http://www.bobvila.com/articles/how-to-paint-a-wood-floor/#.VO9ZeZV0xYc

And how about a Houzz link to the same subject? [https://www.houzz.com/magazine/how-to-paint-your-hardwood-floors-stsetivw-vs~7140096[(https://www.houzz.com/magazine/how-to-paint-your-hardwood-floors-stsetivw-vs~7140096)

Also, I saw comments in the above articles about people very concerned about refinishing the floors to a stained finish at a later date. We did exactly that - painted breakfast nook floor and remained that way for 10+ years. Eventually decided to have them professionally refinished along with additional hardwood flooring in our home.... it was no problem for OUR refinisher to do a beautiful job for us. YMMV, just our experience.

I do NOT remember that I used a primer before the paint either. However, if I were to do this again TODAY, I would use INSUL-X primer as it is very highly reviewed by the pro-paint forum people (I also used it on my newly painted kitchen cabinets but can't testify personally as to the longevity of the product... just know what I read online. lol)

Good luck to you!