Welcome back to the Church!
Firstly, what the Catechism of the Catholic Church says about sin:
We need to be primarily aware of God’s love and forgiveness, to prevent ourselves from succumbing to scrupulosity, living in fear and seeing sin in places where is actually is not.
Your priest in Confession can help you to find the true balance.
You are aware of your human weakness. As soon as you become aware of immoral thoughts, then ask God’s help, and do what you can to distract yourself from any thoughts that might lead to sin. Temptation isn’t sin, unless we deliberately seek it, it becomes sin when we accept a temptation and dwell on it.
It can be difficult to overcome if it’s a habit, but never give up hope, try, and try again.
Remember always, the two commandments of Jesus that sum up the commandments, to love God above all, and others as ourselves.
Remember that when Jesus described the judgement of souls His stated criteria was whether or not we have lived lives of practical kindness to others, which can be as small as a smile and kind word, but also necessary in other needed practical acts of kindness. He said that what we do kind deed for other, we are also doing them for Him, in loving them we are also loving Him. This focus draws oneself out of that focus on self that is more inclined to lead to sin.
The Judgement of the Nations
‘When the Son of Man comes in his glory, and all the angels with him, then he will sit on the throne of his glory. All the nations will be gathered before him, and he will separate people one from another as a shepherd separates the sheep from the goats, and he will put the sheep at his right hand and the goats at the left. Then the king will say to those at his right hand, “Come, you that are blessed by my Father, inherit the kingdom prepared for you from the foundation of the world; for I was hungry and you gave me food, I was thirsty and you gave me something to drink, I was a stranger and you welcomed me, I was naked and you gave me clothing, I was sick and you took care of me, I was in prison and you visited me.” Then the righteous will answer him, “Lord, when was it that we saw you hungry and gave you food, or thirsty and gave you something to drink? And when was it that we saw you a stranger and welcomed you, or naked and gave you clothing? And when was it that we saw you sick or in prison and visited you?” And the king will answer them, “Truly I tell you, just as you did it to one of the least of these who are members of my family, you did it to me.” Then he will say to those at his left hand, “You that are accursed, depart from me into the eternal fire prepared for the devil and his angels; for I was hungry and you gave me no food, I was thirsty and you gave me nothing to drink, I was a stranger and you did not welcome me, naked and you did not give me clothing, sick and in prison and you did not visit me.” Then they also will answer, “Lord, when was it that we saw you hungry or thirsty or a stranger or naked or sick or in prison, and did not take care of you?” Then he will answer them, “Truly I tell you, just as you did not do it to one of the least of these, you did not do it to me.” And these will go away into eternal punishment, but the righteous into eternal life.’
May God continue to bless you, having given you the wonderful gift of your return to the Sacraments.