Lady Grace has a wonderful selection of bras, sizes 32-58 and cup sizes ASA-L. This is a US company but they do ship overseas. Check their website at:www.ladygrace.com
They do offer instruction for sizing.
Huge breasts are no picnic. They cause all kinds of health problems, including back pain. Some women have been driven by this to have breast reduction surgery, but there is no guarantee that they will not continue to grow after the surgery.
Try finding a shop that custom prints shirts and have one made that says "Excuse me, my face is up there (with an arrow)" or "Talk to the face, not the breasts". Or even "God must REALLY love me. See what he gave me?" Or you could simply bend down a little and put your face right into the speaker's face. Or have a little fun with it - say "you want a closer look?" and push them out further! That's usually enough to embarass most people into apologising. But honestly, people just can't HELP but look. So don't hide it, learn to live with it. Smile when people stare. Wave at them. If you can afford it have your blouses and shirts tailor-made to fit your figure. Make the most of what you have and be proud. You are what you are. Accept it. Make sure the rest of you looks good - face and hair especially - to draw some attention away from your bustline.
In case you are wondering, I have also had a big bustline from age 12 when every other girl in school had either no bust or fried egg-sized bustlines. Now I am size 42F. My big bustline has always been part of me. I went to a high school prom once in a fairly low-cut dress and one of the girls made the comment "showing a bit of boob, aren't you?". (She, of course, barely had any). My retort was a smile and "Well, some of us have boobs to show" which got a laugh from her date, and mine.