How Can I Stop Bein Over Possessive over My Girlfriend?

Me and my girl have been dating since July of 2008. we love each other to death, and we were always together. now, her family had to move to Florida in january and it really hurt bad! but we made a vow that we would still be together because im graduatin and i got accepted to a college in Florida. Now! the thing iz, with me being the older and more independent one i've been the one to really make alot of the big desicions and and especially with me being the guy i really have to do alot of work, shes just a junior in high school so theres only so much she can do. she tells me she'll never hurt me and that she'll never cheat on me and i kno its true, but for some strange reason i found myself becoming very over protective and possessive. her family has alot of fincancial issues so i have been worried alot about her because tey might get kicked out of their home so i been really worried. plus with all of the hard hard hard work ive been doin to reconnect with her u cant help but get kinda "attached". plus, my whole life ive experienced nothing but loss. my parents both abandoned me when i was a baby, two of my exes who i really cared about cheated on me usin the famous "he's just a friend" excuse. and what really makes me possessive is that just like them, she has alot of guy friends so i tend to put up a red flag. and with this possessiveness its pushin her away and i hate it and i want my girl n me to be the way we were but i ned help with this over possessiveness. please help....ive given all the details i can give on my situation.