Hi Dreaming,
I can really relate to how you are feeling about this, but as a guy. Last year I was suddenly single and when going out with my friends, seeing the attention they received from from girls out it also made me wonder what was wrong with me.
Honestly, all I can tell you is to just stick it out. It takes a while for you to find your feet again in social situations like that, and once you are truly comfortable with being single and not overthinking thats when your confidence will attract guys.
In the meantime, have you thought about trying apps like Tinder? Even if you’re not interesting in meeting anybody that way, I found its a good way for you to practice building that confidence back up.