I am a muslim girl and I am committed.My parents don't know about this relationship.Will they get punished for this on the last day?
Asalam u Alaykum
If you know that this is haram in islam (and it is!) and can avoid it. Then your parents won't be punished, but you even though knowing and still persisting will be punished.
To add your parents will be punished if they didn't tell you such thing is a sin. Even otherwise they will be asked of their neglect towards you, and even perhaps punished for it. Because in Quran "Allah says, Children are a trust to their parents"
It is never late until you die (which doesn't alert or inform of its coming) Just say Astagfirullah by heart and foget the OP, no contacting back.
In a Hadith it is written that, Allah mentions
"You will be asked that was this world so small for you to avoid sinning"
Your current condition is from Allah as a trial and your current mindset towards this situation is from shaytan!. Don't get angry over this, but remember it when you are calm.
Dear Sister, "Don't put your everlasting Aakhirah in danger for few pleasing moments of this world".(This is from me). Even to add Allah protects you within legal islamic marriage and not outside it.
Insha Allah, You too will grow old so will I and others then you will understand in clear vision of your past that what you did was wrong indeed. Go ask someone you know of who has done such thing in past
May Allah forgive me if I mentioned something Wrong, and guide us all to the right path.