Sheikh I have done so many Sins for about 8 years and now I feel like commiting suicide. I have stopped sinning just less then 2 years ago. I am doing lots of good deeds to wipe away the bad effects of those sins. Qiyam al layl with 1000 ayah, quran memorisation, learning quranic Arabic, pray all sunnah raka. Nothing seems to be working quickly can you advise me.
This is satan messing with your mind so that you would quit all these good things you are doing as such things burn him!
All what he wants of you is to stop repenting and to go back to your sins.
Suicide is one of the major sins in Islam that would admit you to hell forever.
If you continue repenting and abandoning sin, you will be among the righteous beloved servants of Allah and such feelings would go away but this requires time and appreciation that Allah has guided you.