Wearing a 36D

The band is flat in the middle at the frond and doesn't ride up at the back

The only problem I can see is the cup is too big maybe? It's not obvious from the front but is from the side.

I've lost some weight which is why it doesn't fit anymore because I used to fill the cups :'( My old 38C size doesn't fit either.

I don't have the time or energy to go out and get fitted so I'm going to order loads and return loads because it's free so I might as well try :) which sizes would you recommend trying?