A safety is a school that is highly likely to accept you, that is affordable, and that you would be happy to attend. Unless you’ve run the Net Price Calculator (NPC) at all of your safeties, none of them are a safety for you based upon your family’s budget (and demand for CS at U. Mass - Amherst). I would recommend adding U. Mass - Lowell or a different in-state public as a possible safety.
Also, make sure that your safety is a school you would like to attend. For instance, there’s been a recent thread of a student with good stats whose only acceptance her family was willing for her to attend was her in-state flagship. She’s miserable and wants to transfer. Make sure that any school you apply to is one you would be happy to remain enrolled at for four years.