Glad to assist.
For the sake of argument, let's say the child is mine. My concern is the cost associated with the whole thing. I have a security clearance, and financial stability is a very important part of keeping that clearance. I can ill afford to lose my clearance, which could then force me out of the Army, which would then mean the loss of a retirement.
I am not seeing how this would affect your clearance. As a potential father she could later pursue you for costs, and you could then directly create an agreement with the medical professionals to help pay for part of her expenses. But you are not required to cover them all--this is her child, same as yours, and expenses are shared and not borne by one person.
I'm willing to marry her, just for the sake of the medical coverage that she would receive from the military. We spoke about a prenuptial agreement, and she lost it - I'm afraid of her taking everything I have if I don't get one. It seems like I'm damned if I do and damned if I don't - which really is the lesser of two evils?
I cannot tell you what is the lesser of the two evils here as I am not your attorney. But purely going by what you are stating, it appears this person is not out primary for love but for protection and medical insurance (and later for support). That is typically not a healthy way to start a relationship. Using financial means to hold you is not a good long-term solution, and there is likewise an ability to pay for this without marriage, especially if you are not sure this person has your best interest at heart.