I feel so depressed and i dont know why!?

me and this girl have been through alot together. she broke my heart last summer. and i never really got over her or moved on. i tried everything. but i see her all the time and i just know shes the one for me. now this summer we are kinda startin back up again. we decided we are just gunna act like we are goin out to see if it would really work. cuz she doesnt wanna start bein serious right away and then have it end up in a bad way and then not be friends. so we are just seein how things go for now. but sometimes it just seems like she doesnt wanna be with me. im always callin her. always askin her if she wants to do something. she never calls me or anything like that. and so when im not with her. i feel soo depressed. i mean i just wanna be with her but when im not with her i get bad thoughts run thru my mind. its makes me so depressed sometimes. i dont know what to do! i want this to work so bad..!