Spectra S1 Breast Pump Confusion

Please help. FTM here. I bought the Spectra S1 pump and the standard flange that comes with it (24mm) does not fit my nipple. Im currently 30 weeks pregnant and obviously i have not started out pumping. My current nipple size when i measure today is 1cm so 10mm. What flange size should i look for? Im so confused and overwhelmed with everything that’s out there. #firstbaby #pregnancy #advicepls