Part 2; please read part 1 first.

As I was saying before the accursed character limit interrupted:
1/ The expression "starting from the fact" doesn't add any real meaning. The fact is that you fell asleep late, so you can simply state that. 2/ You can BE in bed, but you SPEND TIME in bed. You can use either one, but can't mix them. In this case "spend time" is more relevant. 3/ I split the sentence into two because they really represent two different ideas. Separating them with a semi-colon would also be OK, but a comma let the sentence run on a bit too long in my view. 4/ "Frankly speaking" is Ok, but not when paired with "I have to say"; you're repeating the fact that you're saying something.

The streets here in Genoa were more crowded than as usual today, because my house is just beside the Genoa Stadium and today there was an important football match there.

1/ "Beside" is OK here, but it would be more common for a native speaker to say "alongside" or "next door to".

I have been in that stadium once. , my My team Naples played against Genoa, so I could do no better than to go there to support my team. , and I'd say it was a great experience even though the match ended 0-0.

This sentence runs on a bit too long, making it harder to read. I would break it up as shown.

After the mass I have taken took a stroll to Decathlon, which is a sporting items goods store. , and to To be sincere honest, there's nothing I like better than spending some time in that store,; I really enjoy it.

1/ I understand why you used "have taken" here; you're essentially coming straight from the passato prossimo tense in Italian (ho preso una passegiata). Which is sort of right, but not here. In this context you would want something closer to the imperfetto form; "prendevo una passeggiata", though even that's not an exact translation. It's not that "I have taken" is never right in this context but it would NORMALLY only be used if it is something that you have just completed. A man's phone rings and it's his wife, wanting to know where he is. He might say "I have taken a walk down to the shops." However when he's home, after the trip has been completed and his wife asks where he has been, he would not say "I have taken" but rather "I took a walk down to the shops". 2/ Sporting items is not exactly wrong but sporting goods is more common. 3/ "Sincere" and "honest" have overlapping meanings to some extent, but that's not the real problem; "to be honest" is an idiom in English, "to be sincere" isn't. 4/ You need to use either the infinitive ("there's nothing I like better than to spend") or gerund ("there's nothing I like better than spending") here.

After lunch and after having studied a bit of English I have watched some Series A football games just before falling asleep for a regenerative nap. That was my Sunday; nothing special but this is a lesser fact.

I don't think you'd find many native speakers saying "regenerative nap", but it's poetic enough that I opted to leave it in. "But this is a lesser fact" is more of a problem; it raises the question "lesser compared to what?" I would probably say something like "but enjoyable all the same".

Your English is quite advanced. Most of the issues are relatively minor. This is part 1 of the correction.

Day 2- A quiet and lonely Sunday.

1/ Weekend isn't hyphenated. 2/ Future expressions generally need two words in English, while in Italian a single word will suffice; for example verrà indicates "it will come" in Italian but in English you need the two words "will come". 3/ There was a spelling mistake in enjoYing, but I think it's better to rephrase that anyway. The weekend itself is for enjoying, but the sentence is really talking not about the weekend but about the hope that it will come quickly. The expression that I used above explains why that hope exists. 5/ "The" family is OK, and it is certainly clear enough which family is meant, but I feel that it's better to be specific when you first use a noun; "our" family rather than "the" family which could, in theory, refer to another specific family.

Living far away from everyone of in my family, the weekends are becoming days as which are just like the others;, actually the sooner they end, the better. Anyway I'm not here to complain, as well as and I don't want to write a moving novel, therefore let's talk about the beautiful things I've done today :) (Is it a bit ironic?)

"John is a member OF my family", but "there are 6 people IN my family". As a rule of thumb if you're referring to specific, identified people as being part of your family use "of", but if it is just general people in your family then use "in".  I understand the context in which you were trying to use "as" here, but it cannot stand alone like that. Another way of saying what I've put above would be "which are the same as", but it does need the extra words. "as well as" would be used when you DO want to do something else, not when you don't. "I want to write a complaint, as well as a moving novel". I'm not sure about that last sentence; "a bit ironic" in what way?

Starting from the fact that last Last night I fell asleep quite late (it was about 2 a.m) so this morning I would have been spent much more time in my warm bed, however . However I decided to go to mass in a church which is just in front of my house. I haven't been going to mass for several months, and frankly speaking I have to say that going to mass makes me feel much better.

. (To be continued because I've fallen foul of the accursed character limit again.)