You know, in a way I'm kind of thankful that I haven't gotten engaged till now.
Every couple months I look at back and think "well it sure would have been crazy getting engaged with those finals." More importantly I feel like I've changed. Especially since I've started dating. For example, I think it's really valuable that I learned how to balance learning and grad school decently. I don't think I would be as committed to learning if I had gotten married earlier. Then I think but now-well now it's different. Now I'm ready. I've learned all my lessons. Why haven't I gotten engaged yet?
It's important to keep things in perspective. I know it's hard, at least for me. There is a real desire to wallow in depression or self-pity. Or look at how other people are so happy. Or count the engaged people in your class or the number of people you dated who are engaged now. But realize, What's good for them is not good for you. Maybe you haven't learned all your lessons. Maybe you haven't accomplished everything you need to accomplish. And...I know this is hard to accept...maybe you're just plain old not ready for marriage yet. Hashem knows best. You'll get engaged when it's best for you. Just don't give up hope.