For what it’s worth, you have a nice style of writing. 
hey you have 2 things going on here…one is that you can’t shake the feeling that you should’ve gotten into a school where others would have said, “no way! You got in there?” And the 2nd is that you’re worried that the school you did choose is not a good fit and you’re not sure whether it’s because it’s not prestigious or whether it’s simply a bad choice for you. So who knows…but I will say that sometimes kids transfer and bring their unhappiness with them, so to speak. But other kids transfer and truly find a better fit. It’s worth you really thinking this over.