super rn, what you're feeling sounds very normal, for one your age and at this stage of your life. Goodness, dh and I were married for 14 yr before we had kids, as we felt we just "weren't ready!" Please don't feel guilty for feeling what you do. You're to be commended for your honesty, and you sound like you have both feet firmly on the floor.
Are there more tests planned for your mom? How is she feeling? Wait and see what's going to happen, and take your cues then. I'm glad you're there for your mom. Imagine what she's going through, hearing the dx. A lot of times ppl "know" what's going on, they just are afraid to get checked out. You couldn't have known by such vague symptoms that this was what it was. Don't kick yourself for not being able to foretell the future, nor for the inablility to perform diagnostic scans with your eyes and your feelings.
Ramblings, here. sorry. Keep us posted. My thoughts and prayers are with you.