I get flashbacks from meditation also. There's research out there suggesting meditation might not be appropriate for all people effected by trauma, especially ones with unresolved trauma or cptsd...

I was told that the process of "being in your body" is hazardous if you are still actively working to dissociative from it. For me, beating exercises and meditation bring me back to my abuse. Bathing is a direct trigger, while meditation and being present force me to acknowledge the body flashbacks.

If it's something that does not work for you, I would suggest to set it aside until you can work through some of the trauma stuff in therapy...