For a more thorough answer so you really understand -- oral sex is not a risk for HIV because the virus is very fragile and is inactivated by both AIR and SALIVA. There are enzymes in saliva that break it down. So, whether she had a bit of blood or a lot of blood and you had a gum infection or not, you would not get HIV from giving her oral sex. No one in all the years that HIV has been known has gotten HIV from oral sex. Think about that-- not a true, documented case ever!
The only ways adults get HIV is from unprotected vaginal or anal sex or sharing of IV drug needles. (exposure INSIDE the body).
And this is why you had no risk.