First off Welcome to the board. And to answer your question on why you can't post to the forums at the bottom of the list, those are Archive forums. They are where old threads go when they have lived their life but we feel that their information will still be useful to others (it makes it easier for them to find it later). With the active forums we like to keep things a little bit simpler, rather than expecting people to find just exactly the RIGHT forum to post their question in.
To answer your actual question. I do understand where you are coming from and I think that all of us women go through that insecurity at times, not necessarily with the same questions, but wondering "why would they want to be with me?" or thinking "they are too hot to want to be with me". As has been pointed out those insecurities belong to us and when it comes down to it if someone has expressed and interest in us, then get over it, they are interested. Might they change their mind when they meet you? Maybe, but does that mean it has anything to do with your size or looks? Doubtful, unless your photos are a terrible misrepresentation of who you are, or unless you meet them wearing a girdle and full set of Spanx.