I’ve never felt good enough for girls. What can I do?

I’m 18 yo. The title says it all.

I usually workout, study and read/write stories. Apart from these things, i’ve got some girl friends ( not so many, to be honest… just 2 ). I feel very comfortable while i’m with them, and we usually have a great time together. I’m not interested in them romantically. I got to clarify i generally don’t even have so many guy friends ( again, just 2 ).

But every single time i see a pretty girl ( so, pretty often, considering the only two physical qualities i look for are “good smile” and “slightly curvy body” ), i don’t feel enough.

I don’t feel like and interesting person, also physically ( i’m losing some hair )
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It especially happens when i see couples. Plus, i recently lost some friends cause they didn’t have any time for me left, due to their girlfriends. It sucks.
I’ve never felt good enough for girls. What can I do?
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