Mostly I just need to vent....

I'm going away for just one night tomorrow and today I am already feeling so nervous that I can't sleep.
What's annoying me the most is I've traveled the past three weekends and it seems my anxiety is only growing, despite everything being absolutely fine every single time. First weekend my anxiety was lowest, last weekend it was much higher and today it's crazy high. Things have even been much better than I'd expected! Shouldn't I somehow be "learning" from these positive experiences and getting less anxious every time? I don't even really know what it is I'm worried about now. I do think I've gotten calmer over the flight so... Why do I feel this tension in my body keeping me awake?