It is wrong, but since you didn't know better, you really shouldn't feel bad. If you feel you want to become Catholic, I would strongly suggest you talk to a Priest.
Just to let you know, the only time that it would be okay for someone to partake in Holy Communion without being Catholic is if they would be close to death and did indeed believe that the Eucharist is indeed the Body and Blood of Christ, as Jesus affirmed in the Bible (and the Church also teaches). I should add that those who are Orthodox believers can also partake in Holy Communion as Catholics can also partake in Holy Communion at their Churches-----as they also believe in the truth of the Eucharist as we do.
I will leave you with most of the ending from John Chapter 6 (I would have put in more of the Chapter but it would have been quite long) where Jesus indeed teaches this truth and how sadly and tragically a lot of His followers stopped following Him when He taught this truth (if Jesus was only talkiing symbolically of this---He would have definitely stopped them from leaving and told them He wasn't talking literally):
"The Jews quarreled among themselves, saying, "How can this man give us (his) flesh to eat?"
Jesus said to them, "Amen, amen, I say to you, unless you eat the flesh of the Son of Man and drink his blood, you do not have life within you.
Whoever eats my flesh and drinks my blood has eternal life, and I will raise him on the last day.
For my flesh is true food, and my blood is true drink.
Whoever eats my flesh and drinks my blood remains in me and I in him.
Just as the living Father sent me and I have life because of the Father, so also the one who feeds on me will have life because of me.
This is the bread that came down from heaven. Unlike your ancestors who ate and still died, whoever eats this bread will live forever."
These things he said while teaching in the synagogue in Capernaum.
Then many of his disciples who were listening said, "This saying is hard; who can accept it?"
Since Jesus knew that his disciples were murmuring about this, he said to them, "Does this shock you?
What if you were to see the Son of Man ascending to where he was before?
It is the spirit that gives life, while the flesh is of no avail. The words I have spoken to you are spirit and life.
But there are some of you who do not believe." Jesus knew from the beginning the ones who would not believe and the one who would betray him.
And he said, "For this reason I have told you that no one can come to me unless it is granted him by my Father."
As a result of this, many (of) his disciples returned to their former way of life and no longer accompanied him.
Jesus then said to the Twelve, "Do you also want to leave?"
Simon Peter answered him, "Master, to whom shall we go? You have the words of eternal life." (John:6:52-68)