Dear friend, I am in exactly the same position as yourself! You’ve basically described me entirely, by your post.
My suggestion is that you practice Lectio Divina. This is a mystical practice of reading the Bible at a specific verse or chapter, meditating on it, contemplating what God is saying to you through it, and sitting alone in thought and prayer. You are obviously of the melancholic disposition, which is always afraid of the opinions of others, but only because you love others deeply and feel too awkward to show it. You make grand plans to make charity, love, faith, pious speeches, and good works while at home, but in public you lose your nerve. This is the worst suffering of the melancholic, and can only be overcome by the divine majesty of Christ, who had taken away all our burdens.
You are burdening yourself with a shadow-load! It’s the imagination and memory of what Christ took away from you that is bothering you. He resolved to wash away every evil with His precious blood, and it has stained the cross violently. By the wood of that small tree of life, all the grace of the Universe has flowed into our hearts. As a diffident and shy person by nature, you must absolutely never despair, for God HIMSELF has come and saved us (!!!). This has opened you up to a joy unheard of and unknown.
If you just read the Sermon on the Mount, or the Book of Proverbs, you will see the joy of God. You will really, really, really want to DO the things you plan (with so much holiness) to do. Your innocent love of God and trust and faith in His guiding hand will explode forth if you read, meditate, and contemplate on what the Bible says specifically to you, a person. We are all His poor little ones, but He leads us regardless of that fact; indeed, He leads us despite our poverty and crippled nature! He wants us with Him, and nothing can ever change this fact… not even a few inconsequential slip-ups made by a faithful child.