Why do I constantly have infections (tooth, vaginal, and UTIs), & haven't had my period in 6 months?

I am 24 yrs. old & I have recurring bacteria vaginosis, tooth infections, 2-3 UTIs annually, am always fatigue & lack energy to preform daily tasks, experience poor concentration, periodic fainting and my menstrual cycle ranges between 90-180 day intervals. What could possibly be wrong with me! PLEASE HELP!