Translation:I do not know how it would be if I had not met you.
Well, I got it wrong precisely because of that. When the secondary clause omits the subject, if there's an ambiguity I thought that the best interpretation was that it coincides with the main clause, which in this case was eu. Why would you have to assume a completely different subject? And if not "I", why assume "it" as opposed to he or she or you? Seems like you have to guess. Since the meaning of the sentence doesn't really change all that much regardless of which subject you guess, I think more of those choices should be accepted.
Paulenrique, I had the same question, but have a different idea. I think what you suggest means: "I don't know what I would be if I had not met you." And what Fintan and I are asking is whether "I don't know how I would be (meaning how I would be feeling) if I hadn't met you." Since the conjugation of the conditional is the same for I, he/she, or it there is no help there.