Flange size

Hi mummies, need some advice on my flange size. I have tried 24, 21 and 19mm but it all seem not suitable as my areola seem to get pull in still. At 19mm, my nipples are already rubbing the size (means too small) but the areola is still getting pull in and it feel sore and red. I think this is affecting how much output I have whenever I pumped. Anybody have similar issues, any advice?