not necessarily. Breeding boas can sometimes be full of surprises and unexpected events. Some work like clockwork, ovulation-POS-105 days later = babies. Others don't have any of the signs we look for, such as no noticeable ovulation, no POS, and sooner or later, babies are born. Mine always seems to ovulate, no POS, and somewhere between 100 and 150 (lol) days later, I have babies.
Right now I have an arabesque 100% het albino gravid by a sunglow male, she ovulated, never had a POS, is due may 26th, and is in shed at the moment. They say it is not uncommon for boas to shed approximately half-way through the gestation period.
Moral of the story, don't give up hope or change care of the boa because you think she may not be gravid afterall. I would wait it out, you'd made it this far, whats a few more weeks? They can be very unpredictable, best of luck.