Ahhh betul betul, corong size tu memang penting! Honestly a few of my mum friends prefer beli kat store dulu so dapat try the fit, especially kalau first time, online memang cheaper tapi takut mismatch. Kalau nak mainkan safe, go to Mothercare or pharmacy nearby, they can guide you on which flange size fits your nipple, then kalau dah confirm pakai boleh lah reorder online if cheaper. Don't stress too much though, most pumps come with different flange sizes in the box, so you can test which one comfortable. Good luck with your breastfeeding journey!