Why is my birthday so difficult for me?

So today is my 18th birthday. And I woke up kind of sad. I mean I know I have depression but I woke up with this deep engrained sadness. I tried to put on some fun happy music but I just couldn’t get into it. It’s just been the ‘1000 Forms of Fear’ album on repeat. My family asked me what I want to do for my birthday and I’m completely stumped. I feel weird. I mean, I didn’t expect to live this far and now that I’m here I’m just confused. I don’t know how to feel about today. Everyone around me is happy and is congratulating me on my birthday but I feel empty inside. I don’t feel ready for the future and even though I’ve just turned 18, I’ve already started to face the responsibilities that come with being an adult. Everything feels like it’s moving too fast and I just want to be a little kid again. In all honesty I’m not happy it’s my birthday. I wish I could just skip this day. I hate all the attention on me and I hate how my birthday makes me feel. I hate all the expectations and I’m even dreading getting gifts later. I feel unproductive, I just want to lay in my bed and cry. I don’t get what’s wrong with me. People are supposed to be happy on their birthday, but I’m just not. It’s also like I’ve lost my appetite, I feel nauseas and like I was forced food down my throat. I feel like throwing up, my anxiety is high. I’m just having a terrible day too, so terrible all I can do is laugh. I woke up with a cracked windshield, a flat tire, half my gas tank gone because someone in my family used my car, my favorite skin serum finished, my back hurting, hair a mess, the outfit I laid out the night before looking terrible. And all I could do was laugh. Like I expected this day to go bad. I feel like I’m more at peace with having a bad day than I am having a good one. I just, I don’t get what’s wrong with me. Is this what my life is going to be like forever? Depressed and sad everyday and getting it even worse on my birthday? I’ve talked to my therapist a bit about it but I still can’t seem to just feel better. I wish I was normal.