Well, quite a bit to unravel here.
1. Do I ever scare myself? Answer: No. I apply the amount of pressure that I intend to. I don’t go over for shits and giggles. I’m not sadistic in any way, meaning I don’t really gain joy from the pain or rough sex, but more from her enjoyment of the rough play. Truth is, I have a calm sense of clarity even when passionate so it’s not like when you are in a bar fight and you lose sense of mental control. If you lose sense of control, you need to stop doing this. It’s your job to be the epitome of control. That’s a big part of being in that role.
2. Choking. I’d say read up on it a bit but cutting off blood supply at the jugular and cutting off air supply are two different things and a firm but not death grip is all that is really needed. The duration is something to also be mindful of.
3. The other thing is each submissive woman’s threshold for pain and rough play is different. It’s important you communicate especially early on what is and what is not over the line. I recently read of a Dom who used a 1-10 system when flogging, gaining a sense of what is and what is not tolerable for his sub. I suggest you find out what those lines are in the sand for her and you’ll be better informed to play rough, but responsibly.