If you're not rubbing it in her face, you're not really being rude. I mean, you have the right to be happy and excited about your pregnancy even though other people suffer with infertility. I'd be cautious and try to be sensitive to her feelings, but I wouldn't let it steal your joy. She might not really be mad at you--she might just not be able to handle the sight of a pregnant person right now when she wants to be a mom so desperately, ykwim? Just give her time and be honest with her.
Quoting Commander Shepard:" I am such an ass. My husband's step-brother and his wife have been trying to get pregnant and she recently ... [snip!] ... spending Thanksgiving with her parents and didn't come over when I was down there and I feel like it's because of me. :cry:"
Why are you an ass? It's not your fault, and plus, you're due at the end of January, so it's not like she hasn't known for awhile that you've been pregnant..