As far as sources I’m pretty dry so can’t help with that, but I can give my thoughts.
Attending Sunday Mass is part of our holy obligation. In the Third Commandment, God commanded us to “Remember to keep holy the Sabbath day.” The Sabbath day being Sunday for Catholics. Thus we attend Mass that day to keep holy the Sabbath.
Wearing jeans to Mass is nowhere in Catholic teaching. There is nothing wrong with wearing jeans to Mass. However there is a standard of modesty that should be kept. Remember that we are going before Christ in the Real Presence of the Eucharist. Therefore we should have the utmost respect for Him. We are there to worship the Lord, not to try impress other people with our looks from both ends of the modesty system. I personally will wear a nice pair of jeans to Mass and have never ran into problems doing so.
Emo cutting? Like slitin wrists and all that dark whatnot? Our bodies are temples of the Holy Spirit. We must therefore be careful what we do to them. Harming them with drugs, alcohol, sharp objects, excessive tattoos piercing, would be destructing these temples. If a parent gave you a beautiful car that is unique and irreplaceable, how would you treat it? Chances are you would do the best you could to take care of it. And that’s how the lord wants us treat our bodies.
There’s an idea within the church held by some Catholics today that only guys should be alter servers. The church has nothing against women taking part in the different ministries within the church including alter serving.
As humans. We are giving the free will to make choices in life. Those of us who grow up to be fathers, are obligated to take care, love, shelter their children that they bring into the world, but they are not forced. That being, we have to make the choice whether we are going to put worldly pleasure ahead of them or not. Regardless of the choices we make, all human life is sacred. By hating those who hurt us deeply we do no service to our selves or to the Lord. It doesn’t mean we are required to forget and never mind the illicit behaviors others do to us, and instead act so loving that never even happened. But we should imitate Christ’s willingness to forgive those who hate Him. Hate will never obtain us anything and we should remember that.
This goes back to our bodies being temples of the Holy Spirit. How other view our bodies means nothing to God. Being worried about how we look is simply torture that we don’t need to go through. At 13 she has a wonderful life ahead of her and there is nothing good that starving is going to obtain her. Anorexia is a problem that can require serious attention. I encourage you as a mother to do everything you can to help her. It’s not as simple as just eating more food. Anorexia literally makes people feel that they can not eat. I’m not a doctor by any means, but at least for now have her take vitamin supplements. Perhaps this all stems from the lack of a loving father, but whatever is needs attention and help. Talking to a good spiritual director and/or Psychologist would be a good idea.
You and her with be in my Prayers. Peace of Christ be with you.