Bitter-Sweet Feelings on Halfway Day

Today is the halfway point of my exchange year. I've been in Germany for 150 days, and I have 150 days before I return to America. To say that this day snuck up on me would be false, as the thought of this day has been nagging me from the back of my mind for a couple of weeks now. Yet in a way, it seems too sudden. I've been kind of like a kid counting down the days until Christmas and feeling like it will never come, with the exception that today is not like Christmas, and I didn't want it to come.
Despite being a milestone in my exchange year, this day gives me a bit of a sad feeling. Ever since I've arrived in Germany, I've been counting up. First I counted hours, then days, then weeks, and finally months. Now that I've been here for five months, it's time for me to start counting down.
It makes me feel a little bit panicky to think that, from this point on, I have less days ahead of me, than I do behind me. There are so many things I want to do before I leave. I want to travel, hang out with my friends, bond with my host family, and improve my German. There are so many things that I know now that I wish I knew at the beginning of my exchange, namely, language skills, important parts of German culture, and little tips and tricks for making my exchange more successful. I think that if I could start a ten month exchange knowing what I know now, that things would go incredibly smoother. But I can't do that, and exchanges aren't meant to be smooth, and I just have to make do with the time I have now.
It's a shame that I'm only spending a half year with my new host family, because they are incredibly lovely people, and after just a few weeks here, I already feel right at home. This evening my host mom told me that I'm welcome back any time. I don't even have to call, I can just show up at their door one day. And if they aren't home, then I can just go over to a neighbor's house for a while.
I'm glad I can face the last five months knowing that I'm always welcomed back. That's the hardest thing for me about traveling; I'm never sad about leaving home, because I know that home is always there, and I'll be back eventually, but who knows when I'll be back here?
They say that exchange is not a year in your life, but a life in one year. That being said, does that mean I'm having a midlife crisis? Because it feels like I have five months to live. I guess that all I can do now is make the best of the second half of my year. Here's to a good one.