Why do I worry?

I was reading a friend's blog post on not worrying any more, and I can't help but ask myself why do I continue to worry? I lash out at myself as being so weak and scared, time after time. Plumb's "I Can't Do This" is a constant companion mentally as I drown in thousands of pages of readings, dozens of pages of papers to write on things I've never even heard of before, and financial stresses. So before I go any further, I'm going to make two lists. The first is a positives list, the second is my stressors.

Positives:
1) I'm presenting my work in Toronto, Canada, in March.
2) I've made some wonderful friends at CSA.
3) I do my jobs well for the two professors I work for.
4) I have a God who loves me.
5) I prayed at Saint Francis with one of the friars, that I might be able to forgive myself and her, but more myself since I feel I somehow killed the relationship.
6) I've come to accept that I'm never getting that relationship back, and I just keep praying we can be friends again; when we last talked it was like the good old days before dating where we were both so happy and full of life, talking about stupid little stuff as friends.
7) I read the Bible daily now.
8) I just found out my presentation I've been working on for a month looks good to the prof I have to present it to the class of next week.
9) I feel like I understand a lot of the stuff I did not at first when beginning this program.
10) I know that deep down inside, I am a good person, no matter what others may tell me, and what I sometimes tell myself.

Stresses:
1) Drowning in work in this program.
2) Don't know if I passed my stats midterm; everyone tells me I did fine, that I knew my stuff to write 12 pages for 2 questions, but I still feel like vomiting two days later.
3) That I'm never going to find love again. God willing, I will one day find someone to journey through life with me in the Sacrament of Marriage; but my family and some friends are all too keen to point out to me that I'm getting old, that I'm ugly, and so forth. Plus the university's dating policy restricts me essentially from any undergrads and all (literally) my fellow grad students are married or engaged. Do I even deserve to be loved?
4) Living arrangements for next year, will I have a place to live?

I know the Word says not to worry in so many verses, that God will provide. But worry is such an integral part of who I am; "fear is my deepest problem" I once told the woman whose love I lost. It's still true today, and that leaves such a bitter taste in my mouth that despite my best efforts, it remains unchanged.