Vaginal yeast infection. I take m2 tone?

In August 2019 I am having the yeast infection and it keeps coming back every month after periods. I also consult a doctor and she prescribed me medicine like vaginal suppositories and oral medicine and ointment and I also completed 14 days medicine course in January all my reports are normal and ultrasound is also normal. In January my periods also become light so she prescribed me  M2 tone for 2 month then in Feb and march my periods are improved a little bit also the vaginal infection. these two month i am having a little amount of vaginal discharge but still there is redness and itching on labia Majora. And in April my periods are 5 days late from the expected date anf after my period I'm having white vaginal discharge and redness also starting occuring around my vagina. So why this infection is keep coming back it it a yeast infection or something else. And for unregular period should I take m2 tone?