All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad is His slave and Messenger.
It is good for a Muslim to keep quiet except if he/she was to speak good as this is one of the signs of faith. Abu Hurayrah narrated that the Prophet said: “Whoever believes in Allaah and the Last Day, he should say what is good or keep quiet.” [Al-Bukhari and Muslim]
As regards comparing saying what is good and keeping silent, As-Saffaareeni said in his book “Ghithaa’ Al-Albaab”: “What is predominant is that speaking is better as it is for acquisition (of what is good), and keeping quiet is for abstaining (from what is evil), because a speaker achieves more than what a silent person achieves, this is because the best that happens for a person who keeps silent is being safe, and this is achieved by the one who says good in addition to getting the reward of saying good.”
Also, it was reported from Ibn Rajab (Al-Hanbali) that some people discussed in the presence of Al-Ahnaf Ibn Qays which is better: speaking or keeping quiet? Al-Ahnaf said: “Speaking is better because the excellence of keeping quiet benefits only the person who keeps quiet while good speech benefits those who listen to it.”
Moreover, it was reported that a man said to ‘Umar Ibn ‘Abdul-‘Azeez: “A person who keeps quiet while having knowledge is like a person who speaks while having knowledge.” Thereupon, ‘Umar Ibn ‘Abdul-‘Azeez said: “I hope that on the Day of Judgment the one who speaks with knowledge will be better than the other one [who keeps quiet] because the first benefits the people while the latter benefits himself only.”
Hence, speaking good is required and praised, and among speaking good is one’s speaking to keep sociable with his guests and to have good relations with his in-laws and the like. Therefore, a Muslim should not restrict himself to what is less than what makes him sociable with people and removes the lack of communication between him and them even in an artificial manner.
As regards your question whether or not this matter (your shyness) is normal, then the answer is that it can be normal and it might not be normal. In case you fear that this matter may not be normal, then you may consult some trustworthy psychologists.
Allaah Knows best.