I'm single because:
我单身是因为:

I am very, very, very picky. I figure I'd rather be single than be stuck in a relationship with someone I'm not totally crazy about.
我非常、非常、非常挑剔。我想我宁可单身也不要被困在和我一点也不喜欢的人在一起的关系中。

Unfortunately, the few who pass my standards do not seem to like me that way.
不幸的是,少数达到我交往标准的人似乎并不那么喜欢我。

I'm lazy. I don't make much of an effort to meet people and get to know mildly interesting people.
我很懒。我并没有在迎合别人上花费太多精力,也没有去结交稍微有点意思的人。

I'm busy. I work a lot. Also, I do a lot of other things when I'm not at work and most of them do not involve meeting single men.
我很忙,我工作繁重,我在工作以外的时间也有很多其他事情要做,而他们之中的大部分都无关和单身男子见面的事。

I'm shy. I will not make the first move because rejection sucks.
我很害羞,我不会走出第一步,因为被发卡实在是太糟糕了。

I take relationships seriously, that is something I can't help, so I become pretty emotionally involved. This results in me being extremely picky. Also, because relationships are so important to me when I have one, it's not really compatible with my being extremely busy at this younger stage in my life.
我会忍不住很认真地对待情侣关系,所以我会投入很多感情。这就导致我在这方面非常挑剔。也正是因为情侣关系对我如此重要,当我谈恋爱的时候,我将无法将它和我人生里这个较为年轻的阶段中忙碌的生活之间的关系处理好。

Or maybe just because I'm young and don't really know what I am looking for, and thus am commitment-phobic.
或者也有可能只是因为我还年轻,并不知道自己真正想要的是什么,因此害怕给出承诺。

?