First of all, thank you both for the time you dedicated at helping me.
I learned many things by reading your posts.
Back to the topic...
I imported my addresses in electrum.(I know this is a bit silly as I won't be able to recover my keys with electrums seed)
But I prefer electrum over multibit. Anyway, electrum synced in a few moments but I came up with a new problem.
My balance was less than it was shown on my bitcoin-qt. Actually, electrum show 0.02 btc less.
After that, I imported my addresses on blockchain.info wallet in order to see my balance.(watch only addresses)
Sadly, blockchain.info shows the same balance as my electrum wallet.(Again, 0.02 btc less than bitcoin-qt)
Is there a posibility that some addresses from bitcoin core "key pool" hold my coins?
Is there another logical explanation?
And again, thank you all!