I have constant vivid dreams. Often I don't know if things are memories or dreams. Used to be on antipsychotics, is this psychosis starting again?

Confusion. If you're confused about whether your psychosis is starting again, it's a really good reason to see your psychiatrist again. Especially when the distinction between dream and memory gets blurry, it's time to review with a doctor who knows you. Good luck to you.
Possibly. I'm sorry to hear you are having such distressing experiences. It's really great that you are able to identify early signs of your psychosis returning. Unfortunately, your symptoms of difficulty with reality testing, hypervivid dreams, and a feeling something just isn't right are common for folks with emerging psychosis. I would call your doctor and let them know what is happening.
Maybe. Dreams occur while sleeping. If in. A sleep like state could be a sleep disorder. Psychosis is more commonly noises or voices or feeling like receiving messages.