Matt, whilst your quest is very sweet and touching, I must say that the chances of her still being single are almost nil. Polish women still tend to marry quite young and start a family before the age of thirty.
I was unable to find her through any social media sites.
Quite possibly because she now goes under a married name.
However, on the positive side, if you have her address from all those years ago and it was her family home, then the chances are her family/parents still live there. Why don't you send a letter there and see what happens. Be sure to send it by registered post or courier as the Polish postal system is notoriously unreliable.
Or you could try the email address. I have a Polish friend, she's 28 now and she's had the same email address since she was a teenager even though she's since married and changed her name.