Please do not take offense but you are deficient in some basic Catholic catechism. So was I and it made me nuts trying to respond to such comments by other denominations without ready knowledge.
I would suggest starting with a children’s catechism, or a YouCat (for teens) or an old simple catechism that explains the basics. It was really eye opening to read our Church’s beliefs.
I have graduated to the big Catechism but still keep the simpler ones nearby for quick answers. The bigger "Catechism of the Catholic Church " is full of amazing things and references to ideas, issues, and beliefs (with their scriptural references, by the way, to inform those who claim we aren’t scriptural).
I have also found that taking an RCIA class for enrichment, teaching or assisting in a youth catechism, and just reading and refreshing my knowledge by reading the kids’ books have been helpful in making me a better apologist to others with questions or criticisms.