My answer may surprise you -- but you are right, up to a point: God does want us to be happy! Jesus said, "If you... know how to give good gifts to your children, how much more will your Father in heaven give good gifts to those who ask him!" (Matthew 7:11).
But does this mean God doesn't care how we live, and that happiness comes from casting off all restraints and living any way we want to? No, definitely not! God loves us and knows what's best for us. That's why He has told us what's right and what's wrong. Just as a farmer fences his field to keep his animals from danger, so God has provided a "fence" of right and wrong to keep us from danger. True happiness only comes from living according to His will.
I realize that right now you probably don't believe this. Instead, you think happiness comes from indulging your every desire and ignoring God's moral laws. But eventually this will catch up with you, and you'll discover it simply isn't true. Like the writer of Ecclesiastes in the Old Testament, you'll discover that self-indulgence eventually becomes "meaningless, a chasing after the wind" (Ecclesiastes 1:14).
Don't be deceived, but commit your life to Jesus Christ and discover why God put you here. Only He can give you the lasting peace and happiness you seek. His promise is true: "Blessed are those who hunger and thirst for righteousness, for they will be filled" (Matthew 5:6).