Our esteem is found in the Lord - Christ esteem. Self becomes a non-issue when deny self. We die to self and the new nature of God become preeminent in our lives. Our self-worth becomes greater when we see ourselves as part of the body of Christ and we grow in faith towards the gifts He gives each of us inside the Church. If we don't care about how we fit in to the body or don't care about others and serving them, then we have a big problem.
Now the woman or person that discouraged you did no service to God if she said what she did in the wrong way, but if she was warning you about going the wrong way in life and what lays ahead for a life of selfishness, then it may have had worth in listening to.
To have a life where God blesses you, you have to love Him first and not be ungrateful for the life He has given you. If you don't like your body or follow after the world's ideas of perfection, you won't be happy at all, but will find something always wrong with yourself. Get away from loving the world and the garbage it puts in you of wanting everything you see and not being happy with what you have. It can ruin a happy life of health and service to others - making your life a either a curse or blessing on earth to others.
Seek first the kingdom of God and then all the other things in life will fall into place for you. God will bless you with a blessing so big you cannot contain it if you will only love Him first, above everything else, and seek Him and His Kingdom of love.
Hooking up with a non-believer as a boyfriend would be a mistake. If you are weak in faith, then you could end up farther away from God and lost. It's okay to have friends in the world that are unbelievers, and we are to love them, but not follow after their lifestyles of unbelief and sin. They will want us to be like themselves and wonder when we do not do the sins they do, with peer pressure. With peer pressure they will make fun of you if you don't look like and act like them, so find some Christian youth groups to fellowship with and have fun with.
God bless.... I hope you find a fulfilling life in Christ as you journey.
1Jo 2:15 Stop loving this evil world and all that it offers you, for when you love the world, you show that you do not have the love of the Father in you.
16 For the world offers only the lust for physical pleasure, the lust for everything we see, and pride in our possessions. These are not from the Father. They are from this evil world.
17 And this world is fading away, along with everything it craves. But if you do the will of God, you will live forever.
Lu 9:23 Then he said to the crowd, "If any of you wants to be my follower, you must put aside your selfish ambition, shoulder your cross daily, and follow me.
Mt 6:33 But seek ye first the kingdom of God, and his righteousness; and all these things shall be added unto you.
1 Peter 4:1 So then, since Christ suffered physical pain, you must arm yourselves with the same attitude he had, and be ready to suffer, too. For if you are willing to suffer for Christ, you have decided to stop sinning.
2 And you wont spend the rest of your life chasing after evil desires, but you will be anxious to do the will of God.
3 You have had enough in the past of the evil things that godless people enjoytheir immorality and lust, their feasting and drunkenness and wild parties, and their terrible worship of idols.
4 Of course, your former friends are very surprised when you no longer join them in the wicked things they do, and they say evil things about you.
Plus God promises to heal your heart, liberating you to experience His love in a greater way and will send into your life loving people that you will easily and heartily trust! 
