Souraya, we have almost that same problem only in a small dog although big for a Schnauzer about 27 pounds. Perry was very docile when we got him, he is three now and he has decided he will be Alpha. He won't let anyone except people he knows in our house, will not get along with other dogs and plays pretty rough with Daisy. We have always played lovey dovey with our dogs of course because we love them so much and looked the other way at his aggressivness.
In talking to Carrie, we understand our mistakes. He wouldn't let me put on my shoes because that meant I was leaving, I now have him sit while I put my shoes on and he does well, it took repetition for it to work.
He used to pick up a toy, jump on the couch and growl and shake the toy at the kids goig to school, now we make him get down and tell him no and he is doing better. Thanks to Carrie, now she is going to have to work with us in what we do about him being aggressive with other dogs. In the meantime we are working on the other things. My point is it is very hard to see the faults in our dogs because they are so loving to us and we just want to spoil them, but as Carrie says in the long run we better be the Alpha so the dogs show respect to avoid these kind of problems.
Jackie