feeling... ashamed?

Na
Instead of feeling thrilled, I'm feeling sick, exhausted and, ashamed. I have no reason to. I'm gainfully employed and so is my husband, we have good insurance, we are in our mid-30s. But I feel almost ashamed of this pregnancy. Perhaps because I am older? I'm too embarrassed to tell most of my friends. It is as though not having kids was a major part of my identity, that I am now loosing. I am not the woman dreaming of babies. I never felt a biological clock ticking, never felt my ovaries hurting at the sight of an infant. I had degrees, career, travels to pursue instead. But this pregnancy will change all of that. I think I'm afraid of loosing who I am, loosing friendships built off of not being moms, loosing opportunities to do the types of fun things I enjoy in my last few years of being fun and energetic enough to do them. 
I feel horribly guilt for all of this. Has anyone else experienced these feelings?