I say allow her to complete her goals and take her time to get to your engagement/marriage (It's never good to rush into marriage unprepared). No it's not selfish to think about your goals. Why is It that she's very reluctant to talk to her parent's about marriage or to tell them about your plans to get engaged? I understand your discontent at having to wait for several years but like I said, it's best for yourself and your marriage to wait until you are both prepared, take your time. Achieve your goals in and focus on your lives in the meantime so you will be better prepared when married.