Hey :)
Aside from what Lal wrote, I think it is very importaint to say you’re deeply sorry to directly to your parents, with real humility, remorse, understandning and metta and ask them for forgiveness, without expecting them to give you that forgiveness right away.
Also I think that doing something good for poeple you used to harm is very good idea. Like giving a thoughtful gift without wanting anything in return. It really works wonders, at least in my culture.
I think you should be more concerned about THEIR feelings, than your kamma seeds and it should be good.
With metta