My View of the Timeline for the X-Men Movie Universe

I've been re-watching these movies to get my hype up a little bit for the upcoming "X-Men: Days of Future Past", and I've been trying to figure out what is so wrong with the timeline.

I figured out that if I started with the worst of the series, everything will get better from there on forward and so I started with "X-Men Origins: Wolverine". And yes it did... "X-Men" & 'X2", still good and great as the first day I saw them, and when it was time for "X-Men: The Last Stand", it didn't bothered me that much as before because there was "The Wolverine" extended edition (finally some blood and those claws) to fix the series and keep me interested in watching. "X-Men: First Class" I saved for last (my favorite) and my overall judgement of these X-Men movies actually improved a little.
X-Men (7)
X2 (8)
X-Men: The Last Stand (6)
X-Men Origins: Wolverine (3.5)
X-Men: The First Class (9)
The Wolverine (Extended Edition) (8)

X-Men film series (6.9)

Not that bad for a messed up movie universe... actually... it's not that messed up neither. Few things that has yet to be explained, and I hope it will be somehow, are: how is Professor X still walking from time to time, and how is Beast changing back to human form.
I am fine with Sabertooth not being explained why he is the way he is by the time of "X-Men", I don't care for Emma Frost, and we have yet to see what happens with Toad.

So here is my view (and actually the view) of the timeline for the X-Men Movie Universe.