Does an act of contrition cover mortal sins not confessed?

i had a couple of weeks ago got myself into mortal sin,i went to the saturday vigil and i missed confession so i heard somewhere that it is okay to receive communion the euchuist as long as you say an act of contrition,so i did recite it to myself and then went up to receive the euchrist.did i sin?or is the teaching that i heard correct?also i usually go to morning mass and i have a roll and some coffee about 15 minutes before the mass starts am i violating any laws.sincerely humble spirit:)

Dear Humble,

. An act of contrition is sufficient for venial sins, but not for mortal sins. You are not guilty of a further sin because you didn’t know. But from now on, go to confession first—or don’t receive Holy Communion.

The Eucharistic fast from all food, except water and medicine, remains one hour. Have your roll and coffee after Mass. From now on don’t go on what you hear unless you have read or heard it from a reputable source.

Fr. Vincent Serpa, O.P

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