Praise be to Allah.
Give thanks to Allah for having enabled you to repent and regularly pray and read Qur’an. What you said about loving Allah, may He be exalted, loving religion, and being worried about your sins is indicative of much goodness. This is how the believer is: he loves Allah, hopes for His mercy and fears His punishment.
But we advise you to do two things:
1. Think positively of Allah, may He be exalted, for He is kind, most merciful and loving, and He does not let His slave down or dash his hopes. He is as His slave thinks He is; if a person thinks positively of Him, He will give him what is good.
It was narrated that Abu Hurayrah (may Allah be pleased with him) said: The Messenger of Allah (blessings and peace of Allah be upon him) said: “Allah says: ‘I am as My slave thinks I am, and I am with him when he calls upon Me.’”
Narrated by al-Bukhaari (7405) and Muslim (2675).
According to Ahmad (16059) with a saheeh isnaad: “I am as My slave thinks I am, so let him think of Me as he wishes.”
2. Do not overstep the mark with regard to fear and go to extremes therein, for that may lead to despair. As for sins, once a person has repented from them, they are erased and turned into good deeds, so do not let thinking about them paralyze you. Rather you should focus on striving to increase in righteousness and turning to Allah, by doing a lot of acts of worship and obedience, such as praying, fasting, remembering Allah, reading Qur’an, honouring your parents, upholding ties of kinship, and giving people their dues. For life is short, and Paradise is of different levels, and the one who is blessed is the one who strives for the highest levels.
Offer a lot of du‘aa’ (supplication) for your grandmother. If you owed her money, they give it to her heirs, and if the matter was something intangible, then pray for forgiveness for her and speak of her good qualities to those who knew her.
That which is certain cannot be dispelled by doubt. When someone does wudoo’, it remains valid so long as he is not certain that it has been broken. So pray and let your mind be at rest; ask Allah, may He be exalted, to grant you healing and well-being.
We ask Allah to fill your heart with happiness and contentment, and to include you by His mercy among His righteous slaves.
And Allah knows best.