Stress... What is it good for? Absolutely nothing!

So, why can't I stop stressing? My anxiety is so high I feel like my heart is going to jump out of my chest. I stress about EVERYTHING and while this has always been an issue for me, it seems to have become significantly worse.
I'm beginning to think that I have a thyroid issue. I hope I haven't become a hypochondriac and diagnosed myself but I've had lab work done twice since November and my TSH has been high. Much higher than what current research shows is average. I've had the discussion with my doctor but she seems to think it's not an issue. Even after I expressed to her that I had this same issue 15-20 years ago.
All of my symptoms correlate with hypothyroidism: mood swings, anxiety, fatigue, weakness, lowered immune system, problems sleeping. There's more too. With all of the medications I'm already on I don't even know how I could be having these problems.
Instead, when I saw my doctor, she put me back on birth control. She thought that might be the issue. I've been off birth control for over a year. Yes, my periods are worse and I PMS a bit more but I really don't think that's the issue. Now I've been on the damn pill for over a week and I feel even worse.
Yes, I'm going back to see my doctor this Friday. I'm going to insist on a full blood workup of my thyroid. Let's at least rule this out so I feel better. Then we can look at what else may be causing this. Something is wrong.
Yes, I'm Bipolar. I'm anxious. But lately it feels like it's been extreme. I've had a lot of stressors in my life over the past year and a half so maybe that's a contributing factor but I can't imagine it would cause all of this.
They say stress can impact your body in a lot of ways. In the event that it is not my thyroid, how in the hell do I manage my stress so I can be healthy? At this point I'm clueless. I can't afford the things that make me feel better - therapy, acupuncture, massage. I can barely get to yoga class because I'm so tired.
So... stress, it sucks. It's not good for anything. But how come I can't get rid of it?!?!