Airbabe, From what you wrote you sound EXACTLY like me a few months ago. I had the same thought patterns as you when it came to having a heart attack or a stroke. I really, really thought there was something wrong that the doctors weren't catching.
I went to the ER twice in two months, only for them to tell me, after having blood work and ekg, that it was a panic attack. Both times they gave me 1 mg of Ativan through IV and it calmed me in no time. It's called Hypochondria, or in simpler terms, severe health anxiety.
I have now been on Zoloft and Xanax for 3 months and am feeling much better, not 100% yet, but better. This is my fourth time on Zoloft now. I've taken it three times before over the last ten years. I was diagnosed with GAD, panic disorder, and depression when I was 14 years old. I'm now 39, and since starting perimenopause, my anxiety has gotten extremely worse.
Anyway, from what i've read, it sounds to me like you are suffering from anxiety/panic attacks. I have had all of the same symptoms you have. The one that really used to freak me out was the numbness and tingling. One time I had it so bad that both of my arms down to my hands, my neck on both sides up into my head, and my face were tingling. 
That's what sent me to the hospital the first time.
One more thing i'd like to add......STAY OFF OF DOCTOR GOOGLE! The worst thing people like us can do is look up symptoms on the internet, by the time we're done, we have heart disease, cancer, brain tumors, aids, or some other fatal disease. You get what i'm saying? We have to stop trying to self diagnose and listen to what our doctors tell us. They didn't spend all that money, and all those years in medical school for nothing. Take care honey! You'll be fine! ((hugs)) Fox