Thanks a lot for your detailed answer @RaLo4
In the last couple of days, I decided to leave my model as a multi-class classifier, because besides using the same dataset with classes only 0-1, I can diversify my dataset like classes 0-1-2… in the following days. As far as I understood, even if I build the model as a multi-class classifier, I can feed it with a dataset containing only 0-1 labels. I am planning to use again CrossEntropyLoss, but my only problem right now is changing Linear Activation to Softmax.