Love your family. Remember that submission to authority is a moral duty. Not just the authority of the Church, but also your parents. (Of course, God comes first, but… you know that.)
Most people, Catholics included, assume that indulgences disappeared after the reformation. Not that there were abuses with indulgences, but that indulgences themselves were the abuse. I wanted to correct this thinking in my European history class, but I didn’t know enough so I (wisely) kept my mouth shut.
It is true that young people are, in general, naive. I feel like a traitor to all teenagers everywhere saying that, but it is the truth.
It’s also true that young people, in general, go through phases. Your mother may perceive this “catholic” thing as just another phase you will go through while growing up. And with some things - love of Gregorian chant, for example - it’s okay for it to be a phase. Other things - love of God - have to stay.
It is true that people in the Church have done stupid and idiotic things. If you don’t believe me, talk to a protestant. Or, heck, talk to a Catholic - Martin Luther was a priest.
Do you have a driver’s license, or do you live walking distance from the church? Parents (in general) do not enjoy being inconvienced carting teenagers around everythere. It may be partly her annoyance at getting up every day to take you to Mass.
It may also be that she is a bit envious. Don’t say that out loud, but that might be the case. You might be cracking through where she doesn’t want anything to reach. But watch it, don’t assume this to be the case.
Don’t argue. When voices are raised and tempers are hot, communication dies. Go to your room and sulk if you need to, but don’t get into an argument.
Try a polite “why not?” She may say something that you need to hear. Don’t underestimate how much you can learn from her. You know how to double check your information to see if it’s right, so listen to what she says.
And really listen. Don’t dismiss it before she says anything.
Tell her what you’ve learned, and show her (at least tell her about) your sources. Ask her (POLITELY!!!) to explain what she thinks, and why.
Don’t try to argue, or debate even. Be polite. And love. Even ending the discussion with an “agreement to disagree” may be okay.
If you’re careful, you can tell her (POLITELY!!!) that you’re open to changing your views if you see evidence of your views being false.
Study is good, study is wonderful, but the most important thing is love. If you can love, really love, you have everything.
Tell her that the Bride of Christ - the Church - is what (don’t say who, it’ll freak anybody out) you love. Tell her why.
And tell her you love her, too.
Get out of bed and keep going to mass.