I think that you are absolute right that several individual themes can be grouped under a larger, inclusive theme.
Overall, though, I'm not content with a discussion of literature (especially not at the level of a graduate student) that doesn't move past supposedly timeless themes such as choices and consequences, beauty, freedom, and loneliness. Nothing is truly timeless, in my perspective. Things that seem timeless to us only seem that way because they have real meaning to us, in this place, at this moment. Context is everything (again, in my perspective).
I would encourage you to return to the previous discussions of this topic (I've listed two Q&A items below) that address ways in which you might contextualize your discussion. mshurn has convincingly argued that the small town setting is highly meaningful to the play. I would add that the time period (the post-WWII era of prosperity and conformity) should be addressed in any thorough discussion of the play.
I hope that this reply is helpful.