You know, I experienced something very similar after I had sex for the first time 5 years ago. I remember having sort of runny, yellowish discharge that didn't smell but that I never had before I had had sex. I went to my doctor to have my first pap done and it came back normal but she said she thought the discharge was vaginosis and gave me antibiotics.
After I finished the antibiotics, the discharge remained the same. It wasn't causing me any harm or pain, but it was more of a nuisance having to wear pantyliners all the time.
I remember this lasted for a year or so and then it tapered off. I know I got HPV with my first sexual partner (started with ASCUS paps two years after I started having sex with him) so I attribute the change in my discharge to the HPV he gave me.
It doesn't sound to me like you have a yeast infection because I also went back to my doctor after I finished my antibiotics and she gave me a yeast infection treatment, even though my discharge was not clumpy, smelly, nor did I itch or burn down there (as most yeast infections have those symptoms). I did the yeast infection treatment anyway but sure enough, after the 7 day treatment, my discharge remained the same.
I'm not sure if you have the same thing I had, but it sure sounds familiar. Mine eventually tapered off and I haven't had that type of discharge since, despite still having high risk HPV.
If I were you, I'd definitely go see another doctor and explain your symptoms. It could be HPV related, or perhaps even some other type of vaginal infection. Take care!