Men learn how to relate to women first with their mothers. Almost all shy guys have bad experiences with their mothers. It's very difficult sometimes to realize that your own mother does not treat you well emotionally, but it's true. The hard part in standing up for yourself is in realizing that you are not wrong.
Shyness is about always thinking that you are "wrong" or "not good enough." You're questioning yourself all the time. "Am I boring?" etc, etc.
It doesn't matter if you're boring or not, wrong or not, good enough, or not. Because all those things are what other people think. You can not get over shyness, to feel better, by taking seriously what other people think...including, unfortunately, and ESPECIALLY, your own mother.
I should know. To this day, my own mother prefers to stay in denial about her own issues and her own lack of heart. She hides it inside herself because she is still hurting and she is unwilling to work on her own issues.
So, you can't try to get your mother to understand. She isn't interested, or she would not have made a comment like that. She can't help it. She has her own issues, which helped to create yours.
You have to help yourself, and let her do whatever she wants, without worrying about it. This is just my opinion, of course, but it is based on successfully overcoming shyness.
What will make you feel better? Waiting for your mother to understand and respect you, or loving her for not being able to help herself, so you can just move on, and live your life without questioning yourself all the time.
Follow what feels right. The other responses on this thread are just as good.