If you believe in the traditional waiting for marriage - by all means go for it. I never intended to try to change your mind one way or another on that - if that is what you believe in, I think it is good for you to stick to your guns on that. We will have to agree to disagree, of course.
To distill my other thoughts, however...the one thing you need to do for yourself is that you need to figure out how to flirt with guys. Before you can do that, I think you need to figure out how to become more comfortable with men. In fact maybe it's too soon for you to be on a dating site - people may get the wrong idea from you if you are meeting people there...I don't know what to suggest, but surely there is something you enjoy that you can do as part of a group? Try signing up for things in your neighborhood, you might be surprised.
(BTW, you are not alone - I met one girl a few months ago who was not unlike you. She felt we didn't have any romantic chemistry, but she admitted to me that her problem is that she was also unable to talk to men...but that she found me easy to talk to for some reason.)
Until you can figure this out for yourself - it'll be very hard for you to find a guy who will stick with you long enough for you to become comfortable with him. That's why that one guy didn't stick around - he probably felt he gave you a lot of time and attention over three months, but he didn't see any response from you even though you said you did like him. You need to show him that you are interested without being too overt about it - that's what flirting is all about.