Don't worry about your age, it doesn't matter. Just do what you want to do. I think there is a reason that you would need to go to med school in Pakistan. Just take some grad or upper level science classes, explain your W's and reapply. Also, there are some programs that you might still be able to apply to for post baccs. I just VCU's application closed a few days ago, you might still be able to call the program administrator and see if you can apply to it still, that is the one I am starting in August.
At any rate, don't worry about being 25-27, I was always worrying about that also, when I realized that it really doesn't matter, and just looked at the final goal, I became most more comfortable and motivated. It really doesn't matter.