Why am I all of a sudden changing so much?

most likely hormones causing you to grow up because you are well growing up a lot of the changes youve gone through will help you get a girlfriend because not many girls will date a guy whos a slob and likes "inappropriate" jokes and looks like crap because he just puts on whatever clothes he finds that his grandma bought for him 3 yrs ago or whatever and girls usually want the guy to talk to her not the other way around so a lot of it is because you are interested in a girlfriend and thats most likely cause by hormones