I don't know how I'm going go get through this summer

I guess I just need some perspective and words of encouragement.

Since I've started university, I've come to absolutely dread vacations and time off from school. When I'm at school, I have a purpose, I'm independent and I feel like I'm making something of myself. Summer isn't like that. I don't have a car or a driver's license, which is essential for navigating anywhere in the US. My family lives abroad and provides me with some financial support during the school year, but not in the summer because, according to them, I could save all my living expenses by just going home for all of the holidays. Unfortunately for me that means I can't work due to my visa status in the country they live in (there is no hope of changing this) and would basically spend 3 months doing nothing to further my career or benefit my financial status in any way. I'm currently paying rent to live with a relative in the state I go to school in, but I'm terrified I won't actually end up making enough to even pay that, much less to make this whole summer worthwhile.

I've applied to maybe 15 jobs since I've been done with exams, but there's no guarantee I'll actually get one, and then what? Every single day that passes where I'm not working, I feel more and more hopeless. I can't believe it's only been a week since I finished school - I don't know how I'm going to get through three months. I feel trapped, hopeless, and absolutely miserable with my life.