Translation:I could be a doctor, but I am a lawyer.
The stress of the whole Polish sentence is unnatural. Not only this one.
Could this also be translated as "i could have been a doctor, but i am a lawyer"?
I agree with Perrin917693. The English sentense in the question implies little difference between the two, rather than years of study
Well, Perrin's answer is accepted and I won't change it, but it sounds to me more like "Mogłem być lekarzem" - so it's simply Past Tense rather than conditional.
Until recently, there was only one voice - the female one. Now Duolingo is testing another one, a male one. But even if both voices are to stay, I think there is no way of deciding that 'for this and this sentence, every user will always hear the male voice' :