Hiya,
I have the same start like you from 34A .I had 375cc 2 weeks ago and I am now a D .
With the Macom ,you can get the medium size .
With the M&S bras ,you will need size 36 as you need to allow some space for the swelling.I didn’t know about that so I got the 34 and ended up to have to exchange all of them for the 36 ones .
Good luck with your op .x