Joy is one of the gifts of the Holy Spirit. You have joy in proportion to your spiritual maturity. Joy is not depended on your circumstances. Joy is not happiness.

(Galatians 5:22-23 NIV) But the fruit of the Spirit is love, joy, peace, patience, kindness, goodness, faithfulness, {23} gentleness and self-control. Against such things there is no law.

The verses in Isaiah are taken out of context. You have to look at who's talking and who they're talking to. For example:

(Isaiah 54:11-17 NIV) "O afflicted city, lashed by storms and not comforted, I will build you with stones of turquoise, your foundations with sapphires. {12} I will make your battlements of rubies, your gates of sparkling jewels, and all your walls of precious stones. {13} All your sons will be taught by the LORD, and great will be your children's peace. {14} In righteousness you will be established: Tyranny will be far from you; you will have nothing to fear. Terror will be far removed; it will not come near you. {15} If anyone does attack you, it will not be my doing; whoever attacks you will surrender to you. {16} "See, it is I who created the blacksmith who fans the coals into flame and forges a weapon fit for its work. And it is I who have created the destroyer to work havoc; {17} no weapon forged against you will prevail, and you will refute every tongue that accuses you. This is the heritage of the servants of the LORD, and this is their vindication from me," declares the LORD.

God is talking about a future time of blessing for Israel. It has no application for a Christian today.