when do I use "nos" and when do I use "nosotros"?? I'd like to see this site have an extensive grammar component. :-) These questions bother me...
I'm a novice also, but my understanding is that "nos" is not a subject pronoun but an object pronoun. The "we" is implied by "hemos" but the word-for-word translation is something like "We have turned (ourselves) into doctors" with the "nos" corresponding to "ourselves".
The verb I believe is the reflexive verb "convertirse". Convertirse en algo = to turn into something. So therefore the corresponding reflexive pronoun is used. Me,te,se,nos,os.