As far as I know, there is nothing someone can do to not be Catholic once that they have been Baptized into the Catholic Church, you are signed and sealed with the Holy Spirit and I don’t think that even if you went to another denomination and formally declared yourself to be…whatever…, even if you were re-Baptized into them, (which is never necessary, as only one Baptism is necessary), that you are still indeed Catholic.
One other thing, when going to Mass I like to remember that it isn’t about me, but it’s all about HIM. Am I standing at the foot of Calvary with HIM or not? Am I offering myself as a living sacrifice in union with HIM and giving myself over to God the Father in union with the Holy Spirit? It really isn’t about how I feel, its about entering into the Mass.
I will keep you in my prayers, and also urge you to learn more about the gift that you have been given. God bless you on your journey and may your Guardian Angel guide and all the Saints and Blesseds (especially His Blessed Mother), intercede for you before HIM.
Have you ever seen the journey home website?
chnetwork.org/