Wow italy! Beautiful place. I feel that subscribers are a bit of a hit or miss. Some series takes off faster, some slower but if you're consistent and keep putting it out, your voice will be heard eventually. Some of the Korean webtoons have 80+ panels and it takes them awhile to have a huge following too. This is relatively new for me and of course, getting featured helps a lot but here's what I think about a series;
Your readers eventually stay on because of the story and because of you. If your personality comes off and the readers can see it through interaction or through the story or the art of your comic, they'll stay and start recommending to others. Its always good to have a huge number but sometimes they don't serve much purpose. I've seen artists with 50k Instagram followers and when they start oateron, only have less than 20 subscribers. I think building true fans are more important, who knows, theres so many elements to make a successful comic? So Let's all strive to work harder!