Aw, honey, everyone feels this way- those little niggles of doubt over a compliment; the moments of paranoia. I struggle with it: someone will do something and i wonder whether they're really being nice or if their comments have a veiled meaning. Or alternately, they will annoy me and I'll stew for hours over whether it was careless, but not deliberate, or whether there truly was intention behind it. Anyway, I am trying to just 'let it go'- take compliments and seemingly kind comments at face value. For the mostpart, the compliments are true and if you're getting male attention from more than one source you're obviously attractive. Believe in yourself! I know it's a hard thing to overcome- I really do, but when you start trusting and believing it's amazing how much more you glow; how much more confidence you gain and how much energy you'll save through not stewing over it all.
Perhaps you 'tear yourself down' because deep down you believe you're not worthy? I certainly know that it took me years to get over a spate of bullying in y8 and y9 (all my friends turned on me and I had nobody, through sheer jealousy of the fact that I was getting good grades- but they've all wrecked their lives up now- drugs, smoking, failing their GCSEs etc, whereas I have good grades and a Durham Uni place hahahaha *wicked laughter*) and for a long long time (literally until last year) I had such low self confidence. Or is it that you believe you don't deserve to have happiness or that this happiness will never be permanent- it can never last, so why set yourslef up for disappointment? These are only amateur attempts at psycho-analysis: only you can unlock the fundamental reason why and thus have the happiness and freedom you so deserve.