I am not sure from your question if the feeling of derealisation you are experiencing is part of an anxiety disorder that you may have, or if you are experiencing derealisation without other symptoms.

As such it is difficult for me to give you a definitive reply as there can be a number of reasons as to why you are experiencing this.

I am assuming that you have spoken to your doctor. If not then I do advise you to speak with them so that they can rule out any possible physical cause for the derealisation.

Once you know that there is no physical cause, you could ask your doctor to refer you to a psychologist or psychiatrist who is experienced in post natal care. They would be able to assist you further.