Urinary tract infections (UTIs) is the infection that begins in the urinary system when bacteria from the rectal area enter the urethra causing an infection in bladder and/or kidneys. UTIs are caused in 90% of all ages by E.coli found in fecal matter. There are concerns whether birth control
pills raise the risks of developing an UTI. There is no reliable scientific or clinical evidence that links hormonal contraceptives and UTIs. However, it is an observation that women on the pills are more likely to engage in frequent sex and therefore raise the risks of developing an infection. Of course, UTI is not a sexual transmitted infection, but it is the act during sexual intercourse that creates the condition for an infection. It is all anatomy. In women the urethra is short and close to the vagina and anus, allowing bacteria a quick access to the bladder. A perfect scenario of introducing such infection during vaginal intercourse is a penis brushing the anal area and then rubbing its head near the urethral opening. That being said, it is difficult to see how a hormonal contraceptive that contains progesterone and estrogen can initiate or aggravate an UTI. In fact, lack of estrogen (as in menopausal women) is a risk factor for UTIs.
You are right on about urinating and cleaning the vaginal and urethral area after sex to reduce the frequency of recurrent infections. Another simple and natural treatment that may help is drinking unsweetened cranberry juice. Cranberry juice containing sulfuric acid works by preventing bacteria from "sticking" to the walls of the bladder. If the problem persists, I advise you consult a PCP for antibiotic treatments or discuss about other contraceptive methods.