They frankly dont care about how many years you did your IGCSEs in.
At the end of the day, its not your IGCSE results that get you into a University; its your A Level results.
I'm well aware that IGCSEs are inferior to AS + A levels in terms of importance.
Before I went on to give my advice, I'd like to correct this presumption. Your A-Level results do
not outweigh the importance of your IGCSEs. Yes, your conditional offer materializes depending on the grades you obtain in your A-Level exams, but that's virtually all they do for you. Unless you're applying to topnotch universities like MIT, Oxford, Cambridge or Harvard, you don't need your A-Level results to be in the A-A* bracket and most universities settle for B-A, even Cs.
When you apply to almost any university, it's usually much before the A-Level results. The only official statement of your performance and capability are your IGCSEs. As for your AS-Levels, the good and bad news is that although they would reflect your merits too, even if the grades are bad, universities usually oversee it because it's very, very common that students resit their AS components and they consider first-year results to be a 'practice' of sorts. So if you don't have good IGCSE results, you risk getting an offer to begin with.
This is not to depress you or demotivate you. Not at all! In fact, if you're so certain you'll get A-A*s in most of your IGCSEs, you're in the clear. Usually 6 IGCSEs are considered, up to 8, especially the principle subjects (the one you want to major in). So if you get around even at least 6 A*s, you're in the upper slot of students. Even if you don't get those grades or you get them, but you're not satisfied, you can work on your AS Results. AS/A-Level is a HUGE leap from IGCSEs, so don't take it for granted, but if your concepts are clear then you should be able to maneuver it. A good AS-Result is a strong statement about your performance and understanding.
As for universities making considerations and exceptions, it depends on their administrative procedures. If you're applying to a US/UK university, you can always refer to this in your essay/personal statement in a discreet and polite manner, without sounding self-pitying, rather ambitious. Attach any necessary documents like your US High School Reports, teacher testimonials (if allowed) and anything else you feel that could do justice to your plea. If you're a good student as you claim to be, you should ideally have no problem getting into a reputed university. Best wishes! <3
