I would definitely not be offended. There is no reason at all for you to wait because she is pregnant. I think it would be fun to have someone I know be pregnant at the same time. You could share stories, swap maternity clothes, and just be there for each other for support.
Does she and the rest of your family know that you're high risk and everything you have to go through to get pregnant? If they do, then they will know how very much you want this pregnancy and how hard you have to work for it.
It took us a long time to get pregnant with our daughter. It seemed like everyone around me was getting pregnant, except me. Coworkers, friends, family, it seemed like every woman everywhere I went was pregnant. It was so frustrating, because we wanted it so bad, but it was taking such a long time. So, I can totally understand where you're coming from with the emotional rollercoaster. It's tough.
Every baby is a gift, a blessing. Every pregnancy should be celebrated, it's a beautiful thing.
Good luck to you! I'll be sending lots of babydust your way.