The sound was not clear at all for "meu". I guessed at the "m" and the "eu" sounded more like the "el" in "mel" (honey).
The difference is that, in Portuguese, the e in mel is an open vowel, like é, and in meu is closed, like ê. It's something that does not exists in English, and that's difficult to hear.
Thanks a lot. The other day I had an 'aha' moment when I realised that 'minha' is the equivalent of 'tua' and 'sua'.
it's essentially the same, just changing the order of the words a bit and structure of the sentence... It is not my cat: Não é meu gato. The cat is not mine: O gato não é meu.