It is not unusual for people with PTSD to want to know why. The human brain is designed to react to danger and then find reasons merely for survival. Part of the problem with PTSD patients is often others can make comments on them making too many efforts to find the whys. That is something I have addressed for a long time.
However it is really a normal response to any kind of trama or bad experience.

Please, make sure you don't blame yourself in anyway, or allow yourself to feel any guilt for anything in your past. You are a survivor, you have a right to question and learn, but try very hard not to make it worse than it is, unknowingly people with PTSD do "catastrophize" and it isn't about making things worse than they are, it is more about knowing there was a real danger and we truely have to slowly separate what is a real danger from what may remind us of a real danger.

I am not sure what RSA is, is it repeated sexual abuse?

I have used the example of snakes in the past. We learn that some snakes are very dangerous. And if we get bitten by a snake that can be very scary (I was bitten when I was small). So because we don't know which snakes are safe and which are bad, we fear all snakes. By answering the why, which is gaining Knowledge, we can learn to slowly identify the safe snakes very slowly. It takes time, I am glad you have a good therapist that is helping you answer the whys and learn to work out your troubled alarm system from your past.

(((((Hugs)))))
Open Eyes