Period question

Hi! I have PCOS and I am currently on birth control prescribed by my gynecologist and I have been having my period for 2 and a half weeks and the cramps are bad. For context I started birth control when I had had my period for 3 months, which my gynecologist prescribed me with it. During winter break of December 20-January 15 I stopped taking my birth control and started again and for a while I was fine but now I’ve been having my period for 2 and a half weeks. I contacted my gynecologist and she said to keep taking my bc but I’m scared that it won’t go away