wow, both of your descriptions are very similar to my personal experience...

I was also really anxious as a child (and kinda hypomanic, actually, or whatever the childhood equivalent of that would be) - also about illness and being kidnapped, though I was afraid of throwing up and stuff, not of life-threatening illness - those fears came later (heart disease, MS, brain tumor, you name it!) My OCD symptoms also developed and were centered around health/catastrophe.

I was depressed during early teen years (diagnosed with depression/anxiety at 13), then became extremely rebellious and impulsive - I had lots of grand plans, schemes, and fantasies that left my 'boring' friends in the dust (I ended up leaving high school actually). Looking back, it's hard to believe I escaped this era without a drug addiction, an STD, or a felony...I was diagnosed bp when I was 15. Based on my utterly reckless behavior, it's hard to imagine I was feeling anxious about my health, but I honestly can't remember.

late teens I fell into a very deep depression with severe anxiety - and this is also when I started to get heart palpitations, which brought up all the past health-related fears. I developed panic disorder (and my flying phobia) during this time. This would happen again about 2 years later. Many days I could barely move because I was so dizzy and paranoid. I had to leave school for awhile.

My anxiety in general is very physical - I don't have social anxiety at all really, it's more 'existential,' if that makes sense...I would say it is not worry but DREAD. Somehow I see this as separate from my stress-induced obsessive worrying that is about something specific (an idea, some upcoming deadline, etc.). I also feel like I'm in a constant battle with anxiety - it is definitely a force to be reckoned with (I'm pretty sure I have no idea what feeling calm is)

I recently tried Gabapentin, but I can't tell if it's working...

The brain is so magnificent, isn't it!