Don't know if I really have good tips, but I do recognize some things. People asking if I already have found a guy, if I am looking at all and so on. It's difficult sometimes, but I think your reaction really isn't that bad. Depending on who it is that says it to you, you can either be honest or just react somewhat like above.
Normally I just say that I'm busy (and that's true), and that it love has to come from both sides, and that that's not easy to find. Forcing sometimes is never good I think :)
People don't really ask me anymore--they assume I'm married with kids. Yes. lol They say, 'what does your husband do?', or 'what are your kids names?' I usually counter them with sarcastic remarks, and they know it's none of their business. You aren't less of a person because you aren't married. Think of the opportunities you have. You don't have to clear it with anyone if you want to travel or worry about what someone else will think about your purchases. Marriage isn't easy. You are completely free to be and do whatever you want with your money and time. Marriage is about putting up with someone else's bad habits, issues and you have to agree for the most part with what your partner thinks in order to keep peace. Sure there a great things about being married, but think about the great reasons to be single. The rest is just in a Disney movie. It's not all romance and great sex. It's really about compromise and sometimes it's not all that fun and beautiful. Cherish your ability to have your freedom right now. If you do get married and have kids, you will have to change your lifestyle a lot.
As for the other person. She was being rude. There is nothing wrong with being a single woman. Our culture says if you aren't married by a certain age, women at least, there must be something wrong. It's not true. You aren't alone in how you feel, by the way. Live your life fully though. Go where you want to go, buy real furniture and dishes....don't wait for a man to arrive to complete your life and allow you to have nice things.
My advice is say something curt to the question, "Why aren't you married?" Say something like, "You know, I haven't really thought about it." or "Why do I need to be married? Is there something wrong with being single?" That will shut them up. You need to have boundaries. You can't allow people to hurt you like that. No, you don't need to start a fight or a war, but let them know, that how they are talking to you is unacceptable.
I don't know if you do this or not, of course, but don't go around saying how lonely you are, and how you wish a man would come into your life. Only tell your closest friend or relative, and then don't talk about it. That invites that type of conversation, because people want to help you and usually they cross the line. If you don't bring it up, and you counter it with boundaries when someone else tries to bring it up then people will realize your love life is your business not theirs.
Focus on other parts of your life. Focus on what you do have, instead of focusing on not having a serious relationship. Your career, your home/living situation, your entertainment. Don't stop living waiting for a man to fill your life. The upside to that is you will be more desirable. You know? The guy will be more interested in you because you lead a full life instead of waiting for him to make decisions for you. Marriage is a sacrament, a big responsibility and commitment. When you do get married, the plan is to stay married, so cherish your freedom right now. Once you become a wife and a mother, your world will have a new focus.
Just remember for next time: There is absolutely nothing wrong with being single. Doesn't mean you will never be married, or you are going to become a nun. Nothing wrong with being a nun of course either. Really, it's no one else's business what your relationship status is. Be confident, don't apologize and people will learn to back off. They sense your insecurity so they go in for the kill. Boundaries. No one can make you feel inferior without your consent. You are a fabulous person even if you die a spinster with 50 cats. :)
Where possible, change the subject much earlier in the conversation. Maybe like this:
her: No ring?
you: Not yet, but I've got a really great and interesting job that I've been working at since I finished college last year. How are things going for you?
This kind of thing continues to happen when you're single--- the fun thing is that it gets ruder the longer you're single. Generally, at 33, when I get it, it's kind of like "what's wrong with you, anyway?" Because I don't think that's the issue, I don't have that conversation with many people. You're not broken, you're single. As long as you're okay with it (most of the time--- all of us get lonely sometimes, and those of us who believe we're ultimately called to marriage and family feel that for a reason), then don't let people make you feel like you have a disease. The other thing you can do is to end the conversation swiftly but pleasantly, like this:
her: No ring?
you: Not yet---I'm focused on some other things right now, but if you know a nice guy, I'd love to meet him.
As others have said, people aren't trying to be nasty, they're just sometimes clumsy. Steer the conversation to areas that you're comfortable with. With this woman, you could have answered her question and said, "you know, though, I'm doing all the great things we planned for all those years ago..."
I hate these types of relationship questions from family, friends, and coworkers...If I feel comfortable enough, I will open up and explain how things are going, but for the most part I reply back with something similar to this:
"No, I've only just graduated recently so, I'm enjoying being single for the time being. I do date, but am not looking for anything serious right now."
...the topic changes quickly after that.