Welcome to the board :) Reading your story, I could sympathise completely. I felt exactly as you did, in my early 20s. I would cry myself to sleep, wondering what was wrong with me that no brothers had taken interest. I was spiritual, though had a weak family at the time, but tried my very best. I'm not unattractive, yet I couldn't seem to find anyone. I must admit, I never actively sought anyone, rather I prayed that Jehovah find me someone when the time was right. That was what I was always told to rely on, so I did. Unfortunately (in my case and maybe not others), I found a brother via the internet, who turned out to be a total idiot. I was now more lonely being married then I was being single. It happens.
I don't know what to say, because my sister is headed down the same track. She doesn't say much, she's very quiet, but I know she wants to be married and she'll be 24 next month. Searching for a mate within the organisation can become a very small channel. If you indeed want to remain a witness, but marry a non-JW, then you will still be lonely at conventions. You may eventually marry a brother, but chances are he'll be alot older than you, and divorced. Unfortunately for sisters there isn't the same ratio of brothers, so brothers can be choosy, while sisters generally have to take what comes.
I am now a single mum and I find conventions terrible. I am all alone. But, you must remind yourself that even those who profess to be happy aren't always. Sometimes what goes on behind closed doors is an eye opener. My advice would be to enjoy the freedom you have, because if you marry a brother, headship comes into play (Im talking in a JW sense here folks) and you will be expected to tow the line. I don't know you enough to know how you are with authority, but there are some real doozies of brothers out there who take the headship thing to extremes.
There's alot to be considered. But please don't for a second think that there is something wrong with you. I've been there, thought that and married the first one that came along - and it was a crock. Be choosy. But be happy. And, we're all here for you :) I too am still exploring things, having only just begun visiting this board. It's been a real help so far :)