I miss my old self

How do I start writing again? Everything seemed so much easier when I was younger. Back then, I always knew that I would be a writer, that I would be really successful in this field, I just knew it was something that was sure to happen. But now I am 21 and studying medicine. I know it's supposed to be good but I have noticed that my mind has gotten so restless since I entered this field. I want to start writing again, but now it all feels so far away from me. Earlier, writing a story felt within my reach, like an object I could easily grab from my nightstand, but now the concept of a story feels like I am shooting an empty gun into nothingness. To be honest, everything kinda feels like that these days. I am not doing very well in my academics either, I score decent but I study much more than the score I get and it's driving me crazy. I also don't have any friends here, friends with same interests as me, or even anyone I could simply vibe with. Everything just feels out of place. I do have a boyfriend tho, whom I genuinely love a lot. He's a sports guy, plays quite a lot and is also very very good at it. Dare I say so good at it that our whole college knows about him. He is extremely popular too, so much so that pretty sure many people think that he's too good for me, or that he is wasting his time running behind me when he could have literally hundreds of other girls. It just breaks my heart. He has a lot of friends too, and he takes me along with him wherever he goes, but no matter what, I feel like I a burden to him, that I am someone his friends or people around us have to put up with for having him. I have also started to feel very insecure about every single thing, my looks, my personality, my body, I think I might even be having an ed, it's all just too much to take in. I don't feel like a person anymore, I feel like an accessory, with no identity, no personality, nothing. I really miss my old self, something tells me that starting to write again might make me feel better about myself. I hope it does. And I hope to find ways to help myself back again. Any advices are appreciated.