Ok, I'm putting on my MSW hat (I did get in because other people seem to think I'm a very kind person IRL, but I decided to wear the ass-hat, I mean Dr. Hat and make more $ down the line)
OP, you are not alone in your childhood and life experiences. You're really not. Speaking from personal experience. But if you let your hardships define you, you will be doing not only yourself a great disservice, but those you are now called to serve, your future patients.
I agree, it is sometimes hard to realize we are deserving of the blessings that come our way, but the more you think you are unworthy, the less likely you are to overcome obstacles and rise up to your full potential.
I truly mean this in the kindest way when I say, it might help if you get some self-help. Deepak Chopra, Wayne Dyer, watch The Secret...read some therapy books, or see a therapist. You need to own the YOU that UCLA obviously saw in you, and own it before your interview so you can really shine in person.
It may seem like you won the Golden Ticket in Willy Wonka and the Chocolate Factory by getting an interview at FUCLA with a few less stats, but in the end, Charlie turned out to the best, most deserving candidate of that entire chocolate factory because of his character.
And as much as it makes me cringe to cheer up a future Bruin, go get that chocolate factory!
Best of luck to you and fight on!