I had a look online, and was surprised how difficult it is! (I used to work as a researcher for AQA). Then I remembered what it used to be like when I was a 34ff in ordinary underwear, and understood.
Had a chat to a very helpful lady from Brastop.com . They don't have anything, but she suggested the Elomi Energise sports bra, which she said would be comfortable if not pretty.
Some hospitals, and shops, will put pockets into ordinary bras. Perhaps it is worth ringing your BCN and asking her what you should do? She is, after all, supposed to know how to get you sorted.
It may also be worth seeing this as an opportunity to decide whether you might be interested in a reconstruction and reduction. Then, you could end up with a breast size you felt more comfortable with. I went to a 34d, and it was fantastic being able to buy ordinary bras at a bargain price and feeling more comfortable. Unfortunately, I'm now back to one breast and hoping to be a 34b in a couple of years' time.