Should I feel regret for this?

In grade 8, I was really childish, tasteless, and had a bad sense of humour. But now (in grade 9) I think I've matured substantially. I'm MUCH less impulsive, I have greater control of myself, I'm pretty courteous to others and I sound and look older (people say that I look like a grade 11, and my old grade 8 teacher says I sound like a grade 10). And naturally, I'm pretty happy about these changes. But in school, I had this huge regret about my grade 8 year. About how I could've done so much more. How I could've had such a better reputation. How I alienated myself from a lot of people. And how no one could see the new me. All because of my immaturity. Should I be regretting this? I feel like I deserve all this.