How do I turn this around?

I am a twenty year old graduating college this year. I never really worked hard to achieve anything and I got by so far with decent grades without putting much effort by just doing assignments a day before the deadline/cramming everything the day before the exam. At times, I try hard to actually put effort into doing something but I just cannot be consistent. I have been told on multiple occasions that I'm just wasting away my potential. I want to pursue graduate studies next year and I do not think I can continue this way there.

I am also very socially anxious. I started college during pandemic and could not form any friendships as well due to my anxiety and the constant fear of being judged. Once the in-person classes started at college, I do not have any friends and often feel lonely and excluded which has a toll on my mental health.

I do not want to be the "could have been" guy and really want to turn this around. Living in a third-world country, I often see people struggling for opportunities which makes me feel bad for not making use of those that I have.

I have always felt the most at home on HN, be it due to its people or or just the whole culture associated with it which is why I'm now turning to HN for advice. So, how can I be consistent and actually work hard on something that ha impact on people? And how can I get rid of my social anxiety and form meaningful relationships? I highly appreciate any sort of advice.