so is there a TRUE afterlife in Homestuck or is it only the dream bubbles and the thing is are they even souls or are they just the consciousness of the person that's stripped from their body after death and the "true" soul goes to the afterlife (the official one)?

It’s hard to say if the Ghosts in the Bubbles are the true ‘Souls’ or perhaps a ‘copy’ of sorts, but the Dream Bubbles are NOT the True Afterlife of Homestuck. If there’s something like an Afterlife, we have never seen it- After all, Feferi is the one that makes the Horrorterrors blow the Bubbles for them. It’s also dubious if Lord English’ Ghost Killing means they go to the True Afterlife, if there’s one, or if he’s annihilating the Soul completely and leaving Nothing behind, absolute and complete oblivion.

It should be noted that Ghosts do exist outside of the Bubbles- Aradia and the spirits of other Dead Trolls on Alternia seem to be bound to the earthly plane, so either there is no Afterlife and they just remain haunting the world, or those specific Trolls didn’t pass on to the Afterlife because they had unfinished business as is usual with Ghost Stories.