There's Only One (?) Way

Matthew 7:21 “Not every one that saith unto me, Lord, Lord, shall enter into the kingdom of heaven; but he that doeth the will of my Father which is in heaven.”
This seems to contradict what I was taught as a child, and another verse somewhere (James maybe?) that said that good deeds are like filthy rags.
I was always taught that you had to “confess with your mouth, Jesus is Lord, and believe in your heart that God raised him from the dead” in order to be saved (Romans…something). But here, it seems Jesus wants his followers to lead lives that follow God’s will.
But how can we know what God’s will is?
I hear my parents always saying (to an extent) that I’m leading a life against God’s will. I’m not following his plan. I shouldn’t be homosexual.
I work with teens, some are troubled, some are not. I have a committed relationship with one person whom I love dearly. I feel that I am a very spiritual person, and that I try to do what’s “good” and “right” – and, personally, the best I can to do what’s right in the eyes of God.
How then am I living against His will?
I was also taught that if you confess – even just once – you’re saved forever…no matter what you do afterwards. I think this troubles my parents now. I became “saved” when I was young, so according to their rules, I’m saved now.
I don’t know. This verse seems to be very much like an instruction: lead a good life in the eyes of God. Do His will.
I need to pay attention to what others say throughout the Bible.