Wa Alaykum Assalam wa Rahmatullahi Wa Barakatuh,
Dear questioner,
Thank you for your important question.
May Allah, Most High, reward you for your desire to increase in knowledge.
You must repeat the prayers which you are certain that you prayed before the time entered.
The entering of the prayer time is a condition for the prayer’s validity, just like ablution is. If it is absent, the prayer is invalid and must be made up.
(Shaybani, Kitab al-Asl)
Remember, the time you spend in remembering which prayers they were, scheduling when you are going to make them up, and actually making them up is all considered Worship!
Don’t let yourself feel burdened, but rather consider this an amazing opportunity to increase in Worship.
And Allah alone knows best,
[Ustadh] Omar Popal
Checked and Approved by Shaykh Faraz Rabbani