I believe my now Gf is cryptically pregnant from before our relationship.

Me (21M) and my (19F) Gf, got together about 2 months ago now, and since then shes started to show signs of a cryptic pregnancy, (majority of the symptoms) shes currently in a denial phase about it and subsequently wont get tested. The problem is typically cryptic pregnancy wont show any real symptoms until 20 weeks ish. So chances are the baby isnt mine. I have no clue how to approach the situation and ask her to do a test as i guess it isnt my place to ask. I also wouldnt know how i would react if it is true and she has been carrying someone elses child this whole time. Any advice would be much appreciated