Hi f33db4ck,welcome to PC!!!
Just some thoughts........you're going to have to help me out if I'm off target here, OK??!!

It sounds like, although you know things you feel you"should" be proud of, you need the reassurance that someone else recognises
and values those things in you???
Just wondering if you've any bad experiences in the past, either in or out of relationships whereas you've been made to feel "inferior"??? If so it might help to work on some of those issues???
Or perhaps those qualities you're seeing as good about yourself don't necessarily seem as significant to
you?? Maybe you're needing reminders that they actually matter that much to someone else?? Maybe back some of those up with exploring some of your "deeper qualities" (nevermind one's you think other people
might value!!) ones that you can
personally feel good about.........successes........achievements........???
I'm sure there's more to you as well as.......or even different aspects to them you might find more
personally meaningful!!!

Or maybe you're setting
too high standards/expectations of yourself and you're not sure how well you're living up to those, so need reassurance in that area??? Maybe time to give yourself "a break" and acknowledge how well you actually
are doing???
And of course ultimately you shouldn't have to "prove yourself" to anyone, it should be a matter of them liking you for who you are..........with/depute/regardless of any flaws. No-one's going to be perfect!!! And if someone doesn't like you.....no problem......there
will be someone else who
will!!
But with the anxiety maybe have a think about/write down "worst case" scenarios
if.........and then have a go at thinking about/writing down arguements that dispute/discredit those things happening, or even make them not so bad if they did happen because.........
So just some thoughts............like I said, just let me know if I'm off target anywhere

And you might also find these forums helpful in what you're going through as well:
Relationships & Communication - Forums at Psych Central
Steps to Better Self-Esteem - Forums at Psych Central
Alison