I agree that there is a subtle difference between the two constructions, but I’m not so sure it’s necessarily what you’re thinking. Or at least, I’m not sure that it always works that way. I think it depends what kind of verb it is.
Consider these variants:
- I am proud to be a nurse. (ongoing)
- I am proud of being a nurse. (???)
- I am proud of having been a nurse. (no longer)
- I am proud that I was a nurse. (clearly no longer)
- I am proud to have been a nurse. (clearly no longer)
Given those, I tend to view the second as being more like the first than like those following it here. I don’t necessarily see the second as being done with yet. This seems to remain true if the sentences are cast into the past tense.
- She said that she was proud to be a nurse. (ongoing)
- She said that she was proud of being a nurse. (???)
- She said that she was proud of having been a nurse. (no longer)
- She said that she was proud that she was a nurse. (???)
- She said that she was proud that she had been a nurse. (clearly no longer)
- She said that she was proud to have been a nurse. (clearly no longer)
In the last one, the past perfect aspect makes clear that at the time she was stating this, she wasn’t a nurse any longer.
The one thing that the ‑ing version provides that the infinitive lacks is a sense of the continuous aspect. The continuous version emphasizes the ongoing process not the the simple state or condition. The difference may be more obvious with active verbs. Compare:
- I’m proud to call you my friend. (ongoing?)
- I’m proud of calling you my friend. (???)
- I’m proud that I called you my friend. (action complete)
- I’m proud to have called you my friend. (action complete)
This time around, the version with the continuous aspect (12) seems less like the one immediately before it (11) more like those following it (13 and 14).
It may be that there’s some sort of subtle restriction in using the continuous/progressive aspect with the verb here. If so, it might be
the same ones that normally restricts the continuous aspect from being used
with abstract verbs or those related to possession or emotions.
- I’m proud to belong someplace.
- *I’m proud of belonging someplace.
That last one is at best questionable, and is probably ungrammatical.
This may be why active verbs feel different when used with the continuous aspect than other verbs do.