My mom gave me many speeches as well. She was very upset, as was my father. Now it's just not really spoken about and they've gotten over it for the most part. But I did come out when I was 14, 6 years ago. Just give it time and she'll become more accepting.
To answer the question, no it shouldn't. I can see a parent become a bit upset if they were expecting you to have grandchildren. Other than that they shouldn't care.
Edit: OH and my mom is bisexual ( which DOES exist

) so she was a bit more understanding. There are a lot of gays and bis in my family.