Don’t worry huni as they drop they get bigger so don’t worry you’re only 4 weeks PO.
I measured myself a 32F and that’s how Ann Summers measured me.
Measure with a soft tape measure round your ribs just under your boobs if its an even number that’s your band size. If its odd round up to next even number.
Then for the cups measure around fullest part of your bust making sure it’s parallel to the floor
take the band measurement from the cup measurement. Then every inch is a cup size
1 = A
2 = B
3 = C etc etc….
So for example if your band measurement was 32 and bust measurement 36 that’s 4 cup sizes so a 32D..
X x x x