* The goal of this clinical trial is to learn about medication adherence to difference types of vaginal estrogen in women with low levels of estrogen (for example, post-menopausal women) who have recurrent urinary tract infections. Medication adherence means whether patients take their medicine as prescribed. * Another goal of the study is to learn about changes to the skin of the vagina before and after estrogen treatment, using a specialized imaging modality called optical coherence tomography, which is similar to receiving an ultrasound. * A third goal of the study is to learn about changes to the microbiome (all the bacteria that naturally live in our bodies) before and after treatment with vaginal estrogen. The researchers will be looking specifically at the microbiome in the urine and the vagina. Participants will be assigned by chance (like the flip of a coin) to receive one of three possible vaginal estrogen treatments - cream, tablets, or drug-eluting ring. * The main study tests and procedures include an initial visit in which the researchers will collect baseline information about participants and have participants complete a series of questionnaires. * There will then be 3 and 6 month follow-ups in which the researchers will have participants complete additional questionnaires and the researchers also assess whether participants are using the vaginal estrogen treatment that you were prescribed. If a participant is part of the microbiome cohort, they will also be asked to do the following: * a baseline visit in which urinary and vaginal specimens are collected to assess their baseline microbiome. The vaginal specimen collection will involve a q-tip swab inside the vagina; it is similar to a pap smear. * Finally, participants will have an imaging modality performed on their vagina called optical coherence tomography, which allows the researchers to assess the thickness of the vaginal walls and the blood vessel density. This imaging modality involves the insertion of a thin probe into the vagina to obtain the images of the vaginal wall. * These tests will then be repeated at 6 months to assess if vaginal estrogen treatment causes changes to the vagina.