It is definitely a thing! They change daily in the beginning, mine were small one day huge the next one dropped before the other then the other one caught up again but it felt like it took forever and were uneven but fab now don’t panic hun it’s all normal had exact same thing just hit 6 weeks got measured and was aiming for a D cup from a B and currently an F cup so don’t panic they change so much on a daily basis! Hope this helps xx