i think this is common to most practicing muslims.
all of us muslims sometimes, or perhaps even often feel feel anxious because we don't expect Allah's help because we think we are crap Muslims. you get this hollow feeling inside, and are fearful that something bad is gonna happen real soon. i think this feeling is because practicing muslims know all the bad things that can happen. they know that their mother can suddenly get cancer. they know that somebody might suddenly die -- muslims are a lot more sensitive to the changing winds of fortune. and because we put our trust in Allah to protect us, we feel really, really, really, really inadequate when our Islam isn't going so well.
i think the best cure for this is a lot christian optimism. when i was a kid, my dad gave me Norman Vincent Peale's "The Power of Positive Thinking." christians are kindof amazing in that they can sincerely hope for anything, no matter how crappy a christian they are.
this is something for us to appreciate as well. Allah is the most merciful, the most kind, the most generous. remember that -- and hope -- really, really hope and EXPECT Allah to save you, protect you, and avert calamities from your life. you have to have that belief, that hope, and you have to really, really believe -- otherwise you will suffer anxiety often.
happy go lucky is the way to go. boundless, irrational exuberance, and fool-hardy hope is the way to confront life. you must expect from Allah, and you must hope. otherwise shaytan will fill you with anxiety, loosen your hopes, and eat you alive.
btw: christine has a good point about chemical imbalances. my sister gets panic attacks. its a chemical thing, and in cases like that medication is the way forward.