GIVE ANSWERS - English

Hello, I'm a venezuelan language student interested in knowing about some meanings that were transformed when they get to spanish vocabulary. For instance: eventually (for english people) means finally, but for us this has the meaning of occasionally. That's why I want to find out all those changes, given that despite we don't understand it, we use it... Please! Help me... This need us to take a look at our history, I know, but for me, this is really interesting. 

Another question I have:

The following phrase is really bizarre (for me): no matter what your size... 

Why is' your' size? Or why is there a 'what'? I mean, I dont understand why there's a possessive pronoun there.  For me something doesn't make sense, either 'what' or 'your' 

So sorry for my mistakes on this text. Thanks