Well, as an adrenalin junkie myself I can relate to the thrill-chasing, although I have always perceived my own version to be based on instinct weighing up the risk (in terms of meeting people and the things I have done with them), or based on environmental factors I can control (ie, free climbing, where the risk is not dependent on the actions of others).
However, your own exploits bear a striking resemblance to my ex-gf (now my best friend and one of the biggest supporters of my transition). I'm not saying there's an underlying correlation to you, as she had far deeper issues of which her risk-taking was just one of several symptoms and I know nothing about you, but I do know from experience where it can lead.
She would go out of her way to put herself in dangerous situations. It was not a case of seeking death but very much that she didn't particularly care if she lived or died. She used to hang around in the local crack dens, not as a crack user but as an escape from her then life, partly because she found the people there fascinating and non-judgmental. However, she also had a sense of her own invincibility and a self-belief in her own strength and ability to handle herself that was sorely misplaced. One day, one of the girls in the house just flipped and went psycho on her - and having her head repeatedly smashed into a stone floor, unable to defend herself, brought home to her with frightening reality that she wasn't the immortal that she thought she was. It was one hell of a wake-up call. It also very quickly turned her from not caring about living or dying to definitely not wanting to die - she only didn't because someone intervened.
Since then, she uses that as her 'momento mori' moment ('remember we have to die') and in fact that has become her own self-policing catchphrase to remind herself of her own mortality.
As I said, her actions were symptomatic of a much deeper issue that came with several other behaviours and symptoms which may or may not be relevant in your case (she is in long-term therapy). My point is just to say it's something you need to address, and more importantly please, please be careful - don't let it get to the same point before you wake up to your own mortality.