I Think I Grew Up

Hello! I am an 18-year-old girl and have had problems with my friends for some time. I will start with the fact that I am in the company of 5 people, as one of the girls and I have been together since we were children, and we have become friends with the others for the last 2-3 years. I go out with everyone and we have been really close for 2 years now, we spend all our time together and we have always done it. We are all from one city, but I study in another and see them less often. I haven't come home so often for several months, but we keep in touch on the Internet, we hear and write to each other every day, but something in me is different. Everything comes from the last two weeks. Something has changed since the new year, I don't know what, but when I go out with them I feel stupid. We did all sorts of idiocy in the summer, it was super fun, but the "chats" and "things" we did and talked about before, now they are not fun for me. Today I went to the movies with them and then to coffee and I was very ashamed. We were walking on the streets, and they didn't just talk in a very high tone and shout ... then the topics of conversation were about toilets, feces, gypsies and what not. People were looking at us, everyone was dying of laughter, and I was walking aside and I wanted to sink to the ground. At the coffee and at the cinema they got up all the time, danced, mixed their noses, made animal sounds and I realize all this that some time ago when it happened to me I ignored it and died laughing with them thinking "who cares about the opinion to the people around us, I'm a happy kid ".. now when it happens to me I ask myself" what's wrong with them? " all I know is that when I go out with them I am very bored and uncomfortable. I can't leave them, but I can't keep going out with them. When we talk about a more serious topic such as family, life, education, work and relationships ... they react very childishly, somehow their thinking seems limited and childish. I can't just make new friends out of nowhere, it's not easy and I also can't leave them with the excuse "well I thought you were stupid kids and I don't feel good in your company"