All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad, sallallaahu ‘alayhi wa sallam, is His slave and Messenger.
First of all, we praise Allaah for guiding you to becoming upright and we ask Him to make you firm on it until the Day you meet Him.
We bring you the tidings that the Mercy of Allaah is vast, and that He is gladdened when His slaves turn to Him in repentance, and He has promised to forgive anyone who repents. Allaah says (what means): {But indeed, I am the Perpetual Forgiver of whoever repents and believes and does righteousness and then continues in guidance.} [Quran 20:82]
Ibn Katheer said about the interpretation of the above verse: {repents} i.e. he repents from the unbelief, Shirk, hypocrisy or disobedience that he has committed, {and believes} i.e. with his heart {and does righteousness} i.e. with his limbs, {then continues in guidance} i.e. remains steadfast and abides by Islam until he dies." [Abridged]
As regards making up for the missed prayers, the prayers that you performed after their times are make-up prayers, so you would not make up for them. As regards the prayers which you have performed incorrectly by mistake in such a way that such a mistake results in the prayer being invalid, some of the scholars said that it is an obligation to make up for them and some are of the view that you are not obliged to make up for them. They consider that if someone leaves a condition or pillar of the prayer because he does not know that it is an obligation, then he is not obliged to make up for it; this is the preferred view of Shaykhul-Islam Ibn Taymiyyah .
Ibn Taymiyyah said: "The correct opinion concerning all of these issues is that repetition is not obligatory because Allaah has forgiven mistakes and forgetfulness, and because He has said (what means): {And never would We punish until We sent a messenger.} [Quran 17:15] So if someone has not been informed of the Messenger's command concerning a specific thing, then the effect of its obligation concerning such a person has not been established. Therefore, the Prophet, sallallaahu ‘alayhi wa sallam, did not order either ‘Umar or ‘Ammaar when they were in a state of Janaabah (major ritual impurity) to make up for the prayer, as ‘Umar did not pray and ‘Ammaar prayed after having rolled around in dust. Also, he did not order Abu Tharr to make up for the prayer when he was in a state of Janaabah and went days without praying. Also, he did not command the Companion who ate in Ramadan until the white thread became distinct from the black thread to make up his fast. The Prophet, sallallaahu ‘alayhi wa sallam, also did not command those who prayed towards Jerusalem before the abrogation of the verse had reached them, to make up for their prayers.
"Likewise, if a woman experiencing Istihaadhah (non-menstrual vaginal bleeding) goes for a period of time without performing her prayers due to believing that the prayer is not obligatory for her, then there are two opinions regarding her being obliged to make up for the prayers: one view is that she is not obliged to make up for the prayers as reported from Imaam Maalik and others, because a woman experiencing Istihaadhah who said to the Prophet, sallallaahu ‘alayhi wa sallam, 'I had a strong and terrible menses which prevented me from prayer and fasting,' he ordered her as to what she was obliged to do in the future, but he did not order her to make up for the missed prayers; and it has been confirmed to me by a multiplicity of reports that some women and men in the desert and other places, when they reach maturity, they do not know that the prayer becomes an obligation on them; in fact, if it is said to a woman, 'pray,' she says, 'when I become an old lady', believing that it is only old ladies who are required to pray; and there are many old men who do not know that the prayer is obligatory for them. It is not obligatory for such people, according to the correct opinion, to make up for the missed prayers."
The above view has some strength to it, and we believe there may be some flexibility in the matter. However, if you wish to make up for the prayers in order to be on the safe side, then you may do so. In the future, you should strive to observe the obligatory prayers and persevere in being obedient to Allaah. You should also keep death in mind as if you could see it, as this causes one to perform acts of obedience. The Prophet, sallallaahu ‘alayhi wa sallam, said: "Remember the destroyer of pleasures (i.e. death) often." [At-Tirmithi and others]
Consider what you would wish to have done if death were to come to you, and do it now, and consider what you would wish not to have done if death were to come to you, and avoid it now.
Allaah Knows best.