Simple solution would be to ask them -- and tell them the concerns you have. Will probably be a long answer, as it wouldn't be any one thing that clued them in, but a combination of effects, none of which would on their own tip anyone off as individually those things could be the result of many different things. Only someone very knowledgeable about trauma psychology would be in a position to put it all together -- and it's a credit to them that they could. I never had any that specialized in trauma psychology, or that even drew conclusions which pointed to them having acquired any particularly relevant knowledge along the way. None of mine spotted it on their own, nor had any idea how to handle it once I started sharing on the topic.

There have been times that I felt everyone could tell something about me, and in my case that feeling has gone away on its own every time. It may be that you just need time to acclimate to the fact that you're talking about it at all.

Good luck.