uff. man, this is scaring me for a number of reasons.
note: the following is pretty blunt. so, please, excuse my direct approach.
so, now you know you wanna do medicine. what is stopping you? why don’t you go for it? 'cause you’ll be older than your friends, or your classmates? Listen, when you’ll be a 75 years old half dead doc, you won’t look back and say “oh damn I wasted four/five years of my life learning something I didn’t continue with”. Instead, you’ll be glad that you figured out what you wanted to do and you did it despite taking a wrong turn (if you wanna call it that, I wouldn’t) at some stage. You got to where you had to go one way or the other even though it took some more time but you will surely have learned a lot of stuff on the way.
And why do you think your first degree was a waste? You saw a new country, a new culture, and you grew up as a person. And most importantly, you lived on your own and that is a huge education in itself.
Please, please, please, develop the courage to be different. You spent four years growing up and now if you realize that medicine is your calling, go for it. Don’t get bogged down by what falani auntie or uncle will say or not. You have to be honest with yourself. If you stay in your field and don’t enjoy it, will you ever achieve the level you’d like to see yourself at? Maybe you will but it would be substantially easier if you actually enjoyed what you did.
You spent four/five years learning discipline, logic and problem-solving skills. By virute of those spent years, you will bring a different perspective to medicine - that of an older than the average doc in Pak and that of a problem-solver. The purpose of being a doc is to help people. It is very likely that your experience in a different field will help you help your patients better. 'cause after all, it is all about them.
In the end, the decision is of course yours and I apologize for being blunt and presumptuous. But based on what I know about a typical young Pakistani, I think it is only social pressures that are holding you back from doing what you want to and can still do. If I’m wrong in my assumptions, feel free to throw out everything I said. 