This is really frustrating, for some keyword which I want to be ranked high, if you search from google.uk I'm number 3, from every other google at least the top 10. But for google.mx, which would be the best one for my site, I'm number 41 !

I don't understand how there can be such a huge difference, is it something like, I need more links to my site from people with domain names .com.mx ?

and your keywords are???

Remember, different data centers have this thing called different data. You might have a lot more competition on the *.mx search data center.

you might have more competitors on that region..