What's wrong with me?

I hate the question "why are you still single?" and this weekend I was asked it again. For this occasion, I explained my circumstances. That I had a bf but we ended things and so I'm single. And later as the conversation steered toward marriage expectations I agreed with my companion that I go back and forth on whether it's for me or not. It's easy when you meet someone great to have that split-second thought that maybe it could lead to something more and when I'm going after the things I want to do in my life and I barely have time to think, I realize how lucky I am that I don't have to explain my absence to anyone. But the reality of my life plans/desires really hit home today while attending a friend's baby shower. As I stomached the many "oohs, ahhs, and how cutes" about the baby gifts, I realized that I'm not like a lot of women who get their kicks from doing more traditional feminine things. But as I saw the joy on my friend's face when she talked about her pending arrival and how happy everyone else was in the room, I felt a pang of sadness that I don't have someone in my life that I can have kids with. My biggest fear in life is that I'll give in to temptation one day for thinking that I won't ever find the right person to marry and then end up having a child out of wedlock. There. I've said it. And I think out of all the things I've done in my life that should have scared me, I can't believe that the thought of being alone in the world and having a child alone is the one things that completely freaks me out. I look through my phone and I see lots of opportunities lost. There's the young guy who has a girlfriend but shamelessly flirts. The friend of a friend who we can't ever seem to be available at the same time. And there's a list of other professional, sweet guys who I know that aren't the one for me. And because of that, I'm beginning to lose hope. Me- ever the optimist has faith that is dwindling down to less than a mustard seed. And now, every missed call, every text message is just a reminder that I am still waiting for the person who will assist in my feeling that I have everything I want in life and help push me to go after the things I haven't yet accomplished.