Mazal tov on your upcoming wedding!
When you look for a rabbi, you can and should find out his general approach to birth control before seeking his counsel. This is not considered "shopping around" for a psak, since it is important to choose a rabbi with whom you feel comfortable and whose outlook is similar to yours. You personally will need to explain to the rabbi what your concerns are, what factors will preclude pregnancy at this point, and how much time you feel you will need. There is a big difference between asking for 6-12 months, and asking for a blanket heter until you feel ready.
A couple should only seek out the counsel of a rabbi whom they respect enough to be prepared to honor his evaluation of the issue. The rabbi, in turn, must learn enough about the couple's situation to apply his approach appropriately and to explain the factors involved in a way the couple can understand and accept. In this way, it is less likely that a couple would receive a psak that they could not deal with. If they could not deal with it, communication would be strong enough that they could contact the rabbi again with their concerns. A rabbi takes the urgency of a questioner's concerns very much into account.
Rav Yehuda Henkin, the rabbinic supervisor of this site, generally permits a newlywed couple to use birth control for 6 months after the wedding. If you would like to receive a personal ruling from Rav Henkin, please get back to us with more details including your age, and any other relevant factors.
B'hatzlacha!