Unfortunately, no retainer is strong enough to resist the action of the tongue. If we use a fixed retainer (a thin wire bonded behind the teeth), the tongue is able to push all the front teeth forward together, since they are bonded to the wire. If we use a removable retainer of any kind, it doesn't protect the teeth from the tongue during the day. It is entirely possible that, if the tongue's bad habit hasn't been changed, the teeth will shift after treatment and even go back to their original position.
This answer is for general information. Your own case needs an examination by an orthodontist.