You make the best decision you can with the information you have available at the time. If new information becomes available, in this case in the form of your experience at work, that doesn't mean you screwed up before. Just that now you have more information on which to base your decisions going forward.

I've found that even bad job experiences are useful, because you can learn from them. Especially if you're able to learn what really matters to you, and what is less important.

Good luck.