Mazal tov on your engagement!
Our site's rabbinical supervisor, R Yehuda Henkin, does not usually give permission for extended use of contraception when the factor involved is the pursuit of a career. If you would like to have a specific ruling from him, please write back with any other information relevant to your decision.
However, in decisions about contraception, we think it is preferable for a couple to meet in person with a rabbi whose rulings and insight both members accept. The couple can thus also form a relationship with that rabbi and return to him with follow up questions and concerns and can seek his guidance on other matters. The communication and understanding possible in a personal relationship can also enhance the precision of rulings and the observance of halacha.