I am very talkative especially when get to know new people.^^
It is totally OK to be shy or not fluent in English, there's no need to apologize at all!!^^
Speaking up is the key point and everything! After all English is NOT just a subject but a language to USE.
Once you choose to speak up, things will go smoothly^^ Don’t worry.
My favorite words in Japanese for you:
やればマシ!
お楽しみに^^