On life-altering moments

People often ask me why I "choose" to move to the US. That's a tough question. I'm not sure if I ever truly "choose" to move there. It just kind of happened.

I guess it all started with going on vacation to the US. My family travels a lot; my parents are both teachers so we used the summer vacations to explore different countries. We used to have an RV, but after we sold that (after ten years and lots of car trouble in the last few years), we decided to fly and that's when we ended up in the US...twice! I also wasn't all that happy in my high school; I really couldn't see myself making it through junior and senior year at that school. So it was either try to skip a year and graduate early (which I didn't want to do because I didn't want to leave my friends in my class), switch schools (again, not an option because I didn't want to leave my friends), or study abroad (which, granted, meant leaving my friends for a year but I knew I'd be back in the same class with them my senior year.
Studying abroad led to going to undergrad in the US; I quickly got sucked into ResLife (being an RA for three years and an Orientation Leader for one summer; active in RHA and NRHH), suddenly realized you could do that for a career, applied for grad school and you know the rest.

But did I really ever "choose" to move to the US? It's not like I sat down and said, "Yes, I will spend the rest of my life in the US." It was more a series of events, or "life-altering moments" that led to the move. Not that I realized, at the time, that those were "life-altering moments." It was more seemingly unimportant little decisions: picking a spot for our family vacation, trying to get a job at college to pay for room and board, needing something to do for the summer, etc.

Now I can't imagine moving back to Austria; my life, my carreer - everything is in the US. I still miss my family and friends (I have the three most amazing friends from high school) but I wouldn't know what to do here. I catch myself not "fitting" into the culture here, not knowing how to do things (e.g. not bringing a shopping bag to the store...here, if you don't bring your own bag, you have to buy one...a nice way of forcing people not to waste plastic bags but to re-use them...great idea but it sucks when you stand at the counter and realize you don't have a bag with you and have to cram all the chocolate you just bought into the pockets of your jacket). I'm sure I could get used to the life over here again pretty quickly, but would I be happy? Am I happy in the US though?
Tough questions. I'm not sure I know the answers. Sometimes I feel like I'm just drifting along in my life: after high school, I went to college because that was the next step (granted, I went to a different country which was a little out of the ordinary but it was still college), then I went to graduate school because it was the next step, I applied for a job in my field of studies because it was the next step. But now, what's the next step now? Apply for another job? Try to move higher in my career? Try to find a partner and start a family? But is that really what I want or is it just "the next step?"
And what are those "seemingly unimportant decisions" that will later turn out to be "life-altering moments." It'd be nice to know because then I could spend just a little more time thinking about them as I make them.