Most Helpful Guy
Odds are that if guys are not approaching you in person then you need to study your body language. You are most likely projecting that you are not open to being approached.
I wouldn't read much into not finding someone good online. There's usually a reason guys end up on online dating sites.
This is just the tip of the iceberg, but stop being down on yourself. You're not the first pretty girl without a date to the prom.
Most Helpful Girl
I have seen too much of these questions, and they make me feel a little sad for some reason because of how much they try to change themselves for people.
There is absolutely nothing wrong with you. Am I the only one who thinks that 23 is actually still very young?
Anyway, you can start by talking to guys at work or school. It can be about lunch, or just ask them how their day is. It can be a normal conversation, you don't have to stress yourself so much.
Also, I don't think a guy necessarily needs to make the first move because there are some shy ones! Just a thought, maybe there are guys that like you, just shy to approach you? You can just try to approach them for a change.
All the best!