If you are shy to speak English, that is a natural feeling. Everyone is shy to speak a second language, but no one should be scared. This is a great thing that you are doing. Learning a second language is difficult. Most people understand that it is difficult, so they also know that you will make some mistakes... making mistakes is normal. Let me ask you a question. "If I spoke Mandarin to you, and I made a mistake, would you think that I was stupid?" I have tried to learn your language, and if you heard me speaking mandarin, you would see my mistakes, but you would be glad to see that I was trying hard to speak your language. One more thing to think about: You speak Mandarin 100% plus you may speak English 5% = 105%. I speak English 100% plus Mandarin 1% = 101%. So, who is better at languages? I wish I could speak Chinese as well as you speak English. Be proud of the English that you know and never be afraid.