What Causes A Colorless Vaginal Discharge?

I am 14 I have already started my period, But I still get that white/clear/watery discharge stuff on my panties. It is usually normal colors like white ect.. But a few days ago I noticed it was kinda yellow.. It wasn't like clumpy I guess.. It was like one small pile kinda thing..I didn't notice a bad smell though.. Well I didn't really smell it.. Would you really just be able to notice if it smelled? Like you wouldn't have to actually smell it you know.. But I was just wondering should I be worried about a yeast infection or whatever?