yeast infections

I am constantly getting routine yeast infections. Not fun @ all. I'm sexually active & use the nuva ring for protection, leaving it in for 3 weeks & out for one for my period. I've never been pregnant, etc. I'm 24. About 116 lbs a little over 5 foot. I have anxiety disorder & adhd that I take medication for. I am a smoker and a casual drinker. Also I have IBS. Don't know why I'm constantly getting yeast infections. My doctor told me it's just part of being a woman but it's embarrassing to call them for that one pill frequently in order to kill the infection. I've always had very thick whitish discharge && light short periods since I started @ age 7. Any suggestions or advice?