Your post is extremely troubling, because it shows that the state of catechisis is at an all time low. I cannot remember a time when I did not know that missing Mass on Sunday was a mortal sin. You also don’t seem to realize that mortal sin means not only that you cannot receive the sacraments, but that you are completely cut off from the grace of God and if you should die without confessing this sin, you will go to hell. Mortal sin means you are in the same spiritual state now as you were before baptism, when you were born in original sin and belonged to Satan. You are as separated from God as Satan is.
Because your of your ignorance, you may not actually be responsible and therefore not in mortal sin. And I commend you for your resolution not to miss any more Sunday Masses. But still, this is very serious. You should not waste one moment more in confessing this sin. Trust me, the priest will be as kind and compassionate as anyone can be, and he will absolve you of your sins and bring you back into communion with God and the Church. GO TO CONFESSION IMMEDIATELY.
Another very troubling part of your post is you refer to “taking bread.” Do you realize that the consecrated host is no longer bread, but that it is the body and blood of Jesus Christ? Do you know what transubstantiation means: “the doctrine holding that the bread and wine of the Eucharist are transformed into the body and blood of Jesus, although their appearances remain the same.” This means that when the priest pronounces the words of consecration over the bread and wine, they actually cease to be bread and wine and become Jesus Christ himself. It is absolutely wrong to continue to refer to this as bread and wine. It is now the body and blood of Christ. When you take that consecrated host into your mouth, you are not receiving bread, you are receiving the great Lord of the Universe, the One who created you and who poured out his blood on the cross so that you can spend eternithy with him.
I am not blaming you for your lack of knowledge. Someone somewhere failed you along the way. Still, I could just sit down and cry. How many more million young Catcholics like you are out there? We older Catholics have a lot for which we must answer.