I remember thinking that if I could just get to medical school, then I would be happy and fulfilled. Then I thought if I could just match into a surgery residency, I'd be happy and fulfilled. Then it switched to finishing residency. Then passing my general surgery boards. Then finishing fellowship. Medicine and my career didn't give me the fulfilled, happy feeling that I was chasing. Once I was done, I had the same emptiness and thought, "now what?"
OP, if you aren't happy now, and can't find balance in your life, then I'm sorry to tell you that it won't get any easier going forward. Medical school can be variable, but once you hit residency, you'll wonder what you did with all that free time during undergrad.
My advice is to find happiness now. Do whatever you need to get out of the loneliness and emptiness that you are in. Make time to socialize. Force yourself to go out. Your mental health is much more important than medical school. If you need to slow down your class load and graduate in 5 years, then that is perfectly fine. Medical schools aren't going to knock you for that. If you need to take a year off to find what makes you happy, then you should do so.
Medicine isn't going to make you happy or fill the emptiness that you are feeling. On the contrary, it will likely make it worse. I strongly advise you to take care of yourself.