By definition, a choice is under your control or it is no longer a choice.

–noun
1. an act or instance of choosing; selection: Her choice of a computer was made after months of research. His parents were not happy with his choice of friends.
2. the right, power, or opportunity to choose; option: The child had no choice about going to school.

Yes. Of course, things are a little different if you are under 18 and have parents to help make them for you. Other than that, yes, you should be taking full responsibility for the decisions that you are indeed making by yourself.

The choices one makes are ultimately under one's control, but many times the circumstances which brought about the need to make a choice, or the timing for making it, fall outside of our control. When this happens, even though the final choice is our own, the options may be limited.

No, I don't believe that the choices you make are under your control. So much of our lives aren't. The fact that you're reading this on a computer screen, for instance. Thought of in one way, this was partially under your parents' control -- they raised you in such a way that facilitated your access to a computer -- but then, that wasn't entirely under their control either. Their grandparents did the same, and theirs before them. Looked at in another way, it's all because you were born under the circumstances you were born in. And compared to the worldwide population, that isn't entirely that likely of a circumstance.

Other day-to-day changes might seem like they're under our control, but they're subject to a lot of factors. Some of them we know about -- for instance, if we're going to have a meeting with our boss, we know that the boss is going to control a great deal of the outcome -- but others are "unknown unknowns." What if we get hit by a car on our way there? What if our boss does? What if six other meetings get scheduled, making this one impossible? The possibilities are infinite.

So no, I don't think our choices are largely under our control. We have to think they are in order to maintain some level of sanity, but we're all just one person pressing buttons with billions of other people, hoping we can beat them all out with a good outcome.