The speaker is looking back on something painful that happened seven years ago, though the poem never says exactly what. The repeated "It's been 7 years" works like a person counting days, steadily reminding themselves how far they've come. Memories still surface now and then, and so does the fear that the old feeling might return, but the speaker says it hasn't, and that they're okay.
The turning point is the idea that every cell in the body is replaced every seven years. The speaker takes this as a kind of rebirth, tied to turning twenty-one. The last three lines repeat "a body" and move from what he has never touched, to what will never feel his gaze, to what he will never feel again. Judging by these lines, someone violated the speaker's sense of safety in their own body. The mood is quiet and defiant, with relief and lingering wariness side by side. It ends on reclaimed ownership rather than anger.