I agree with the other ladies go to the store. I am a size 0-2 and wear have the same bust size as you do (petite from my mother, breasts courtesy my father's sister). What I have found in life to be true about all of my shopping - GO TO THE STORE and try it on. When they are making adjustments, make certain that they take their time and do the measurement correctly (this is very important). When you are petite and busty, your clothes must fit well, for them to look perfect!
The trick that I have been implementing is buy bigger and make smaller. It has been working for me. I bought a size 8 wedding dress (strapless). That way my breasts fit, but the rest of the dress has to be drastically altered. I have to do this with all of my dresses and it usually works out fine.
Good luck!